test: add metadata parser coverage (#11307)

## Summary
Adds tests for metadata parsers

## Changes

- **What**: 
- add test file generation script
- identified & fixed bug in webp exif parsing over-reading
- identified & fix bug in mp3/ogg parser where it would read from a
fixed position instead of relative, causing incorrect reads throwing
RangeError
- added catch in latent + json parsing to resolve errors

┆Issue is synchronized with this [Notion
page](https://www.notion.so/PR-11307-test-add-metadata-parser-coverage-3446d73d36508108ac36dddcec0a54d4)
by [Unito](https://www.unito.io)

---------

Co-authored-by: GitHub Action <action@github.com>

src/scripts/metadata/__fixtures__/helpers.ts

@@ -0,0 +1,48 @@
+import { vi } from 'vitest'
+
+export const EXPECTED_WORKFLOW = {
+  nodes: [{ id: 1, type: 'KSampler', pos: [100, 100], size: [200, 200] }]
+}
+
+export const EXPECTED_PROMPT = {
+  '1': { class_type: 'KSampler', inputs: {} }
+}
+
+type ReadMethod = 'readAsText' | 'readAsArrayBuffer'
+
+export function mockFileReaderError(method: ReadMethod): void {
+  vi.spyOn(FileReader.prototype, method).mockImplementation(
+    function (this: FileReader) {
+      queueMicrotask(() =>
+        this.onerror?.(new ProgressEvent('error') as ProgressEvent<FileReader>)
+      )
+    }
+  )
+}
+
+export function mockFileReaderAbort(method: ReadMethod): void {
+  vi.spyOn(FileReader.prototype, method).mockImplementation(
+    function (this: FileReader) {
+      queueMicrotask(() =>
+        this.onabort?.(new ProgressEvent('abort') as ProgressEvent<FileReader>)
+      )
+    }
+  )
+}
+
+export function mockFileReaderResult(
+  method: ReadMethod,
+  result: string | ArrayBuffer | null
+): void {
+  vi.spyOn(FileReader.prototype, method).mockImplementation(
+    function (this: FileReader) {
+      Object.defineProperty(this, 'result', {
+        value: result,
+        configurable: true
+      })
+      queueMicrotask(() =>
+        this.onload?.(new ProgressEvent('load') as ProgressEvent<FileReader>)
+      )
+    }
+  )
+}

src/scripts/metadata/avif.test.ts

@@ -1,7 +1,76 @@
-import { beforeEach, describe, expect, it, vi } from 'vitest'
+import fs from 'fs'
+import path from 'path'
+import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest'
 
+import {
+  EXPECTED_PROMPT,
+  EXPECTED_WORKFLOW,
+  mockFileReaderAbort,
+  mockFileReaderError
+} from './__fixtures__/helpers'
 import { getFromAvifFile } from './avif'
 
+const fixturePath = path.resolve(__dirname, '__fixtures__/with_metadata.avif')
+
+afterEach(() => vi.restoreAllMocks())
+
+describe('AVIF metadata', () => {
+  it('extracts workflow and prompt from EXIF data in ISOBMFF boxes', async () => {
+    const bytes = fs.readFileSync(fixturePath)
+    const file = new File([bytes], 'test.avif', { type: 'image/avif' })
+
+    const result = await getFromAvifFile(file)
+
+    expect(JSON.parse(result.workflow)).toEqual(EXPECTED_WORKFLOW)
+    expect(JSON.parse(result.prompt)).toEqual(EXPECTED_PROMPT)
+  })
+
+  it('returns empty for non-AVIF data', async () => {
+    vi.spyOn(console, 'error').mockImplementation(() => {})
+    const file = new File([new Uint8Array(16)], 'fake.avif')
+
+    const result = await getFromAvifFile(file)
+
+    expect(result).toEqual({})
+    expect(console.error).toHaveBeenCalledWith('Not a valid AVIF file')
+  })
+
+  it('returns empty when AVIF has valid ftyp but corrupt internal boxes', async () => {
+    vi.spyOn(console, 'error').mockImplementation(() => {})
+
+    const buf = new Uint8Array(40)
+    const dv = new DataView(buf.buffer)
+    dv.setUint32(0, 16)
+    buf.set(new TextEncoder().encode('ftypavif'), 4)
+    dv.setUint32(16, 24)
+    buf.set(new TextEncoder().encode('meta'), 20)
+
+    const file = new File([buf], 'corrupt.avif', { type: 'image/avif' })
+    const result = await getFromAvifFile(file)
+
+    expect(result).toEqual({})
+    expect(console.error).toHaveBeenCalledWith(
+      expect.stringContaining('Error parsing AVIF metadata'),
+      expect.anything()
+    )
+  })
+
+  describe('FileReader failure modes', () => {
+    const file = new File([new Uint8Array(16)], 'test.avif')
+
+    it('resolves empty when the FileReader fires error', async () => {
+      vi.spyOn(console, 'error').mockImplementation(() => {})
+      mockFileReaderError('readAsArrayBuffer')
+      expect(await getFromAvifFile(file)).toEqual({})
+    })
+
+    it('resolves empty when the FileReader fires abort', async () => {
+      mockFileReaderAbort('readAsArrayBuffer')
+      expect(await getFromAvifFile(file)).toEqual({})
+    })
+  })
+})
+
 const setU32BE = (dv: DataView, off: number, val: number) =>
   dv.setUint32(off, val, false)
 const setU16BE = (dv: DataView, off: number, val: number) =>

src/scripts/metadata/avif.ts

@@ -407,6 +407,7 @@ export function getFromAvifFile(file: File): Promise<Record<string, string>> {
       console.error('FileReader: Error reading AVIF file:', err)
       resolve({})
     }
+    reader.onabort = () => resolve({})
     reader.readAsArrayBuffer(file)
   })
 }

src/scripts/metadata/ebml.test.ts

@@ -0,0 +1,49 @@
+import fs from 'fs'
+import path from 'path'
+import { afterEach, describe, expect, it, vi } from 'vitest'
+
+import {
+  EXPECTED_PROMPT,
+  EXPECTED_WORKFLOW,
+  mockFileReaderAbort,
+  mockFileReaderError
+} from './__fixtures__/helpers'
+import { getFromWebmFile } from './ebml'
+
+const fixturePath = path.resolve(__dirname, '__fixtures__/with_metadata.webm')
+
+describe('WebM/EBML metadata', () => {
+  it('extracts workflow and prompt from EBML SimpleTag elements', async () => {
+    const bytes = fs.readFileSync(fixturePath)
+    const file = new File([bytes], 'test.webm', { type: 'video/webm' })
+
+    const result = await getFromWebmFile(file)
+
+    expect(result.workflow).toEqual(EXPECTED_WORKFLOW)
+    expect(result.prompt).toEqual(EXPECTED_PROMPT)
+  })
+
+  it('returns empty for non-WebM data', async () => {
+    const file = new File([new Uint8Array(16)], 'fake.webm')
+
+    const result = await getFromWebmFile(file)
+
+    expect(result).toEqual({})
+  })
+
+  describe('FileReader failure modes', () => {
+    afterEach(() => vi.restoreAllMocks())
+
+    const file = new File([new Uint8Array(16)], 'test.webm')
+
+    it('resolves empty when the FileReader fires error', async () => {
+      mockFileReaderError('readAsArrayBuffer')
+      expect(await getFromWebmFile(file)).toEqual({})
+    })
+
+    it('resolves empty when the FileReader fires abort', async () => {
+      mockFileReaderAbort('readAsArrayBuffer')
+      expect(await getFromWebmFile(file)).toEqual({})
+    })
+  })
+})

src/scripts/metadata/ebml.ts

@@ -353,6 +353,7 @@ export function getFromWebmFile(file: File): Promise<ComfyMetadata> {
     const reader = new FileReader()
     reader.onload = (event) => handleFileLoad(event, resolve)
     reader.onerror = () => resolve({})
+    reader.onabort = () => resolve({})
     reader.readAsArrayBuffer(file.slice(0, MAX_READ_BYTES))
   })
 }

src/scripts/metadata/flac.test.ts

@@ -0,0 +1,56 @@
+import fs from 'fs'
+import path from 'path'
+import { afterEach, describe, expect, it, vi } from 'vitest'
+
+import {
+  EXPECTED_PROMPT,
+  EXPECTED_WORKFLOW,
+  mockFileReaderAbort,
+  mockFileReaderError
+} from './__fixtures__/helpers'
+import { getFromFlacBuffer, getFromFlacFile } from './flac'
+
+const fixturePath = path.resolve(__dirname, '__fixtures__/with_metadata.flac')
+
+afterEach(() => vi.restoreAllMocks())
+
+describe('FLAC metadata', () => {
+  it('extracts workflow and prompt from Vorbis comments', () => {
+    const bytes = fs.readFileSync(fixturePath)
+    const buffer = bytes.buffer.slice(
+      bytes.byteOffset,
+      bytes.byteOffset + bytes.byteLength
+    )
+
+    const result = getFromFlacBuffer(buffer)
+
+    expect(result.workflow).toBe(JSON.stringify(EXPECTED_WORKFLOW))
+    expect(result.prompt).toBe(JSON.stringify(EXPECTED_PROMPT))
+  })
+
+  it('returns undefined for non-FLAC data', () => {
+    const buf = new ArrayBuffer(16)
+    const result = getFromFlacBuffer(buf)
+    expect(result).toBeUndefined()
+  })
+
+  describe('FileReader failure modes', () => {
+    const file = new File([new Uint8Array(16)], 'test.flac')
+
+    it('resolves empty when the FileReader fires error', async () => {
+      mockFileReaderError('readAsArrayBuffer')
+
+      const result = await getFromFlacFile(file)
+
+      expect(result).toEqual({})
+    })
+
+    it('resolves empty when the FileReader fires abort', async () => {
+      mockFileReaderAbort('readAsArrayBuffer')
+
+      const result = await getFromFlacFile(file)
+
+      expect(result).toEqual({})
+    })
+  })
+})

src/scripts/metadata/flac.ts

@@ -42,6 +42,8 @@ export function getFromFlacFile(file: File): Promise<Record<string, string>> {
       const arrayBuffer = event.target.result as ArrayBuffer
       r(getFromFlacBuffer(arrayBuffer))
     }
+    reader.onerror = () => r({})
+    reader.onabort = () => r({})
     reader.readAsArrayBuffer(file)
   })
 }

src/scripts/metadata/gltf.test.ts

@@ -1,7 +1,11 @@
-import { describe, expect, it } from 'vitest'
+import { afterEach, describe, expect, it, vi } from 'vitest'
 
 import { ASCII, GltfSizeBytes } from '@/types/metadataTypes'
 
+import {
+  mockFileReaderAbort,
+  mockFileReaderError
+} from './__fixtures__/helpers'
 import { getGltfBinaryMetadata } from './gltf'
 
 describe('GLTF binary metadata parser', () => {
@@ -160,4 +164,20 @@ describe('GLTF binary metadata parser', () => {
     const metadata = await getGltfBinaryMetadata(invalidEmptyFile)
     expect(metadata).toEqual({})
   })
+
+  describe('FileReader failure modes', () => {
+    afterEach(() => vi.restoreAllMocks())
+
+    const file = new File([new Uint8Array(16)], 'test.glb')
+
+    it('resolves empty when the FileReader fires error', async () => {
+      mockFileReaderError('readAsArrayBuffer')
+      expect(await getGltfBinaryMetadata(file)).toEqual({})
+    })
+
+    it('resolves empty when the FileReader fires abort', async () => {
+      mockFileReaderAbort('readAsArrayBuffer')
+      expect(await getGltfBinaryMetadata(file)).toEqual({})
+    })
+  })
 })

src/scripts/metadata/gltf.ts

@@ -165,6 +165,7 @@ export function getGltfBinaryMetadata(file: File): Promise<ComfyMetadata> {
       }
     }
     reader.onerror = () => resolve({})
+    reader.onabort = () => resolve({})
     reader.readAsArrayBuffer(file.slice(0, bytesToRead))
   })
 }

src/scripts/metadata/isobmff.test.ts

@@ -0,0 +1,52 @@
+import fs from 'fs'
+import path from 'path'
+import { afterEach, describe, expect, it, vi } from 'vitest'
+
+import {
+  EXPECTED_PROMPT,
+  EXPECTED_WORKFLOW,
+  mockFileReaderAbort,
+  mockFileReaderError
+} from './__fixtures__/helpers'
+import { getFromIsobmffFile } from './isobmff'
+
+const fixturePath = path.resolve(__dirname, '__fixtures__/with_metadata.mp4')
+
+describe('ISOBMFF (MP4) metadata', () => {
+  it('extracts workflow and prompt from QuickTime keys/ilst boxes', async () => {
+    const bytes = fs.readFileSync(fixturePath)
+    const file = new File([bytes], 'test.mp4', { type: 'video/mp4' })
+
+    const result = await getFromIsobmffFile(file)
+
+    expect(result.workflow).toEqual(EXPECTED_WORKFLOW)
+    expect(result.prompt).toEqual(EXPECTED_PROMPT)
+  })
+
+  it('returns empty for non-ISOBMFF data', async () => {
+    const file = new File([new Uint8Array(16)], 'fake.mp4', {
+      type: 'video/mp4'
+    })
+
+    const result = await getFromIsobmffFile(file)
+
+    expect(result).toEqual({})
+  })
+
+  describe('FileReader failure modes', () => {
+    afterEach(() => vi.restoreAllMocks())
+
+    const file = new File([new Uint8Array(16)], 'test.mp4')
+
+    it('resolves empty when the FileReader fires error', async () => {
+      vi.spyOn(console, 'error').mockImplementation(() => {})
+      mockFileReaderError('readAsArrayBuffer')
+      expect(await getFromIsobmffFile(file)).toEqual({})
+    })
+
+    it('resolves empty when the FileReader fires abort', async () => {
+      mockFileReaderAbort('readAsArrayBuffer')
+      expect(await getFromIsobmffFile(file)).toEqual({})
+    })
+  })
+})

src/scripts/metadata/isobmff.ts

@@ -274,6 +274,7 @@ export function getFromIsobmffFile(file: File): Promise<ComfyMetadata> {
       console.error('FileReader: Error reading ISOBMFF file:', err)
       resolve({})
     }
+    reader.onabort = () => resolve({})
     reader.readAsArrayBuffer(file.slice(0, MAX_READ_BYTES))
   })
 }

src/scripts/metadata/json.test.ts

@@ -0,0 +1,91 @@
+import { afterEach, describe, expect, it, vi } from 'vitest'
+
+import {
+  mockFileReaderAbort,
+  mockFileReaderError,
+  mockFileReaderResult
+} from './__fixtures__/helpers'
+import { getDataFromJSON } from './json'
+
+function jsonFile(content: object): File {
+  return new File([JSON.stringify(content)], 'test.json', {
+    type: 'application/json'
+  })
+}
+
+describe('getDataFromJSON', () => {
+  it('detects API-format workflows by class_type on every value', async () => {
+    const apiData = {
+      '1': { class_type: 'KSampler', inputs: {} },
+      '2': { class_type: 'EmptyLatentImage', inputs: {} }
+    }
+
+    const result = await getDataFromJSON(jsonFile(apiData))
+
+    expect(result).toEqual({ prompt: apiData })
+  })
+
+  it('treats objects without universal class_type as a workflow', async () => {
+    const workflow = { nodes: [], links: [], version: 1 }
+
+    const result = await getDataFromJSON(jsonFile(workflow))
+
+    expect(result).toEqual({ workflow })
+  })
+
+  it('extracts templates when the root object has a templates key', async () => {
+    const templates = [{ name: 'basic' }]
+
+    const result = await getDataFromJSON(jsonFile({ templates }))
+
+    expect(result).toEqual({ templates })
+  })
+
+  it('returns undefined for non-JSON content', async () => {
+    const file = new File(['not valid json'], 'bad.json', {
+      type: 'application/json'
+    })
+
+    const result = await getDataFromJSON(file)
+
+    expect(result).toBeUndefined()
+  })
+
+  describe('FileReader failure modes', () => {
+    afterEach(() => {
+      vi.restoreAllMocks()
+    })
+
+    it('resolves undefined when the FileReader fires error', async () => {
+      mockFileReaderError('readAsText')
+
+      const result = await getDataFromJSON(jsonFile({ nodes: [] }))
+
+      expect(result).toBeUndefined()
+    })
+
+    it('resolves undefined when the FileReader fires abort', async () => {
+      mockFileReaderAbort('readAsText')
+
+      const result = await getDataFromJSON(jsonFile({ nodes: [] }))
+
+      expect(result).toBeUndefined()
+    })
+
+    it('resolves undefined when reader.result is not a string', async () => {
+      mockFileReaderResult('readAsText', new ArrayBuffer(8))
+
+      const result = await getDataFromJSON(jsonFile({ nodes: [] }))
+
+      expect(result).toBeUndefined()
+    })
+
+    it('resolves undefined when reader.result is null', async () => {
+      mockFileReaderResult('readAsText', null)
+
+      const result = await getDataFromJSON(jsonFile({ nodes: [] }))
+
+      expect(result).toBeUndefined()
+    })
+  })
+})

src/scripts/metadata/json.ts

@@ -6,21 +6,28 @@ export function getDataFromJSON(
   return new Promise<Record<string, object> | undefined>((resolve) => {
     const reader = new FileReader()
     reader.onload = async () => {
-      const readerResult = reader.result as string
-      const jsonContent = JSON.parse(readerResult)
-      if (jsonContent?.templates) {
-        resolve({ templates: jsonContent.templates })
-        return
+      try {
+        if (typeof reader.result !== 'string') {
+          resolve(undefined)
+          return
+        }
+        const jsonContent = JSON.parse(reader.result)
+        if (jsonContent?.templates) {
+          resolve({ templates: jsonContent.templates })
+          return
+        }
+        if (isApiJson(jsonContent)) {
+          resolve({ prompt: jsonContent })
+          return
+        }
+        resolve({ workflow: jsonContent })
+      } catch {
+        resolve(undefined)
       }
-      if (isApiJson(jsonContent)) {
-        resolve({ prompt: jsonContent })
-        return
-      }
-      resolve({ workflow: jsonContent })
-      return
     }
+    reader.onerror = () => resolve(undefined)
+    reader.onabort = () => resolve(undefined)
     reader.readAsText(file)
-    return
   })
 }
 

src/scripts/metadata/mp3.test.ts

@@ -0,0 +1,106 @@
+import fs from 'fs'
+import path from 'path'
+import { afterEach, describe, expect, it, vi } from 'vitest'
+
+import {
+  EXPECTED_PROMPT,
+  EXPECTED_WORKFLOW,
+  mockFileReaderAbort,
+  mockFileReaderError
+} from './__fixtures__/helpers'
+import { getMp3Metadata } from './mp3'
+
+const fixturePath = path.resolve(__dirname, '__fixtures__/with_metadata.mp3')
+
+afterEach(() => vi.restoreAllMocks())
+
+describe('MP3 metadata', () => {
+  it('extracts workflow and prompt from ID3 tags', async () => {
+    const bytes = fs.readFileSync(fixturePath)
+    const file = new File([bytes], 'test.mp3', { type: 'audio/mpeg' })
+
+    const result = await getMp3Metadata(file)
+
+    expect(result.workflow).toEqual(EXPECTED_WORKFLOW)
+    expect(result.prompt).toEqual(EXPECTED_PROMPT)
+  })
+
+  it('returns undefined fields when file has no embedded metadata', async () => {
+    vi.spyOn(console, 'error').mockImplementation(() => {})
+    const file = new File([new Uint8Array(16)], 'empty.mp3', {
+      type: 'audio/mpeg'
+    })
+
+    const result = await getMp3Metadata(file)
+
+    expect(result.workflow).toBeUndefined()
+    expect(result.prompt).toBeUndefined()
+    expect(console.error).toHaveBeenCalledWith('Invalid file signature.')
+  })
+
+  it('does not log an invalid signature for a valid MP3 sync header', async () => {
+    const errorSpy = vi.spyOn(console, 'error').mockImplementation(() => {})
+    const buf = new Uint8Array(16)
+    buf[0] = 0xff
+    buf[1] = 0xfb
+    const file = new File([buf], 'valid.mp3', { type: 'audio/mpeg' })
+
+    await getMp3Metadata(file)
+
+    expect(errorSpy).not.toHaveBeenCalled()
+  })
+
+  it('does not log an invalid signature for a valid ID3v2 header', async () => {
+    const errorSpy = vi.spyOn(console, 'error').mockImplementation(() => {})
+    const buf = new Uint8Array(16)
+    buf[0] = 0x49
+    buf[1] = 0x44
+    buf[2] = 0x33
+    const file = new File([buf], 'valid-id3.mp3', { type: 'audio/mpeg' })
+
+    await getMp3Metadata(file)
+
+    expect(errorSpy).not.toHaveBeenCalled()
+  })
+
+  it('extracts metadata that spans the 4096-byte page boundary', async () => {
+    vi.spyOn(console, 'error').mockImplementation(() => {})
+    const metadata =
+      `prompt\0${JSON.stringify(EXPECTED_PROMPT)}\0` +
+      `workflow\0${JSON.stringify(EXPECTED_WORKFLOW)}\0`
+    const metadataStart = 4090
+    const size = metadataStart + metadata.length + 4
+    const buf = new Uint8Array(size)
+    for (let i = 0; i < metadata.length; i++) {
+      buf[metadataStart + i] = metadata.charCodeAt(i)
+    }
+    buf[size - 2] = 0xff
+    buf[size - 1] = 0xfb
+    const file = new File([buf], 'large.mp3', { type: 'audio/mpeg' })
+
+    const result = await getMp3Metadata(file)
+
+    expect(result.workflow).toEqual(EXPECTED_WORKFLOW)
+    expect(result.prompt).toEqual(EXPECTED_PROMPT)
+  })
+
+  describe('FileReader failure modes', () => {
+    const file = new File([new Uint8Array(16)], 'test.mp3')
+
+    it('resolves undefined fields when the FileReader fires error', async () => {
+      mockFileReaderError('readAsArrayBuffer')
+
+      const result = await getMp3Metadata(file)
+
+      expect(result).toEqual({ prompt: undefined, workflow: undefined })
+    })
+
+    it('resolves undefined fields when the FileReader fires abort', async () => {
+      mockFileReaderAbort('readAsArrayBuffer')
+
+      const result = await getMp3Metadata(file)
+
+      expect(result).toEqual({ prompt: undefined, workflow: undefined })
+    })
+  })
+})

src/scripts/metadata/mp3.ts

@@ -1,21 +1,28 @@
 export async function getMp3Metadata(file: File) {
   const reader = new FileReader()
-  const read_process = new Promise(
-    (r) => (reader.onload = (event) => r(event?.target?.result))
-  )
+  const read_process = new Promise<ArrayBuffer | null>((r) => {
+    reader.onload = (event) => r((event?.target?.result as ArrayBuffer) ?? null)
+    reader.onerror = () => r(null)
+    reader.onabort = () => r(null)
+  })
   reader.readAsArrayBuffer(file)
-  const arrayBuffer = (await read_process) as ArrayBuffer
+  const arrayBuffer = await read_process
+  if (!arrayBuffer) return { prompt: undefined, workflow: undefined }
   //https://stackoverflow.com/questions/7302439/how-can-i-determine-that-a-particular-file-is-in-fact-an-mp3-file#7302482
   const sig_bytes = new Uint8Array(arrayBuffer, 0, 3)
   if (
-    (sig_bytes[0] != 0xff && sig_bytes[1] != 0xfb) ||
-    (sig_bytes[0] != 0x49 && sig_bytes[1] != 0x44 && sig_bytes[2] != 0x33)
+    (sig_bytes[0] != 0xff || sig_bytes[1] != 0xfb) &&
+    (sig_bytes[0] != 0x49 || sig_bytes[1] != 0x44 || sig_bytes[2] != 0x33)
   )
     console.error('Invalid file signature.')
   let header = ''
   while (header.length < arrayBuffer.byteLength) {
     const page = String.fromCharCode(
-      ...new Uint8Array(arrayBuffer, header.length, header.length + 4096)
+      ...new Uint8Array(
+        arrayBuffer,
+        header.length,
+        Math.min(4096, arrayBuffer.byteLength - header.length)
+      )
     )
     header += page
     if (page.match('\u00ff\u00fb')) break

src/scripts/metadata/ogg.test.ts

@@ -0,0 +1,74 @@
+import fs from 'fs'
+import path from 'path'
+import { afterEach, describe, expect, it, vi } from 'vitest'
+
+import {
+  EXPECTED_PROMPT,
+  EXPECTED_WORKFLOW,
+  mockFileReaderAbort,
+  mockFileReaderError
+} from './__fixtures__/helpers'
+import { getOggMetadata } from './ogg'
+
+const fixturePath = path.resolve(__dirname, '__fixtures__/with_metadata.opus')
+
+afterEach(() => vi.restoreAllMocks())
+
+describe('OGG/Opus metadata', () => {
+  it('extracts workflow and prompt from an Opus file', async () => {
+    const bytes = fs.readFileSync(fixturePath)
+    const file = new File([bytes], 'test.opus', { type: 'audio/ogg' })
+
+    const result = await getOggMetadata(file)
+
+    expect(result.workflow).toEqual(EXPECTED_WORKFLOW)
+    expect(result.prompt).toEqual(EXPECTED_PROMPT)
+  })
+
+  it('returns undefined fields for non-OGG data', async () => {
+    vi.spyOn(console, 'error').mockImplementation(() => {})
+    const file = new File([new Uint8Array(16)], 'fake.ogg', {
+      type: 'audio/ogg'
+    })
+
+    const result = await getOggMetadata(file)
+
+    expect(result.workflow).toBeUndefined()
+    expect(result.prompt).toBeUndefined()
+    expect(console.error).toHaveBeenCalledWith('Invalid file signature.')
+  })
+
+  it('handles files larger than 4096 bytes without RangeError', async () => {
+    const size = 5000
+    const buf = new Uint8Array(size)
+    const oggs = new TextEncoder().encode('OggS\0')
+    buf.set(oggs, 0)
+    buf.set(oggs, 4500)
+    const file = new File([buf], 'large.ogg', { type: 'audio/ogg' })
+
+    const result = await getOggMetadata(file)
+
+    expect(result.workflow).toBeUndefined()
+    expect(result.prompt).toBeUndefined()
+  })
+
+  describe('FileReader failure modes', () => {
+    const file = new File([new Uint8Array(16)], 'test.ogg')
+
+    it('resolves undefined fields when the FileReader fires error', async () => {
+      mockFileReaderError('readAsArrayBuffer')
+
+      const result = await getOggMetadata(file)
+
+      expect(result).toEqual({ prompt: undefined, workflow: undefined })
+    })
+
+    it('resolves undefined fields when the FileReader fires abort', async () => {
+      mockFileReaderAbort('readAsArrayBuffer')
+
+      const result = await getOggMetadata(file)
+
+      expect(result).toEqual({ prompt: undefined, workflow: undefined })
+    })
+  })
+})

src/scripts/metadata/ogg.ts

@@ -1,17 +1,24 @@
 export async function getOggMetadata(file: File) {
   const reader = new FileReader()
-  const read_process = new Promise(
-    (r) => (reader.onload = (event) => r(event?.target?.result))
-  )
+  const read_process = new Promise<ArrayBuffer | null>((r) => {
+    reader.onload = (event) => r((event?.target?.result as ArrayBuffer) ?? null)
+    reader.onerror = () => r(null)
+    reader.onabort = () => r(null)
+  })
   reader.readAsArrayBuffer(file)
-  const arrayBuffer = (await read_process) as ArrayBuffer
+  const arrayBuffer = await read_process
+  if (!arrayBuffer) return { prompt: undefined, workflow: undefined }
   const signature = String.fromCharCode(...new Uint8Array(arrayBuffer, 0, 4))
   if (signature !== 'OggS') console.error('Invalid file signature.')
   let oggs = 0
   let header = ''
   while (header.length < arrayBuffer.byteLength) {
     const page = String.fromCharCode(
-      ...new Uint8Array(arrayBuffer, header.length, header.length + 4096)
+      ...new Uint8Array(
+        arrayBuffer,
+        header.length,
+        Math.min(4096, arrayBuffer.byteLength - header.length)
+      )
     )
     if (page.match('OggS\u0000')) oggs++
     header += page

src/scripts/metadata/png.test.ts

@@ -1,11 +1,19 @@
-import { describe, expect, it } from 'vitest'
+import { afterEach, describe, expect, it, vi } from 'vitest'
 
-import { getFromPngBuffer } from './png'
+import {
+  mockFileReaderAbort,
+  mockFileReaderError
+} from './__fixtures__/helpers'
+import { getFromPngBuffer, getFromPngFile } from './png'
+
+afterEach(() => vi.restoreAllMocks())
+
+const PNG_SIGNATURE = [0x89, 0x50, 0x4e, 0x47, 0x0d, 0x0a, 0x1a, 0x0a]
 
 function createPngWithChunk(
   chunkType: string,
   keyword: string,
-  content: string,
+  content: string | Uint8Array,
   options: {
     compressionFlag?: number
     compressionMethod?: number
@@ -20,12 +28,11 @@ function createPngWithChunk(
     translatedKeyword = ''
   } = options
 
-  const signature = new Uint8Array([
-    0x89, 0x50, 0x4e, 0x47, 0x0d, 0x0a, 0x1a, 0x0a
-  ])
+  const signature = new Uint8Array(PNG_SIGNATURE)
   const typeBytes = new TextEncoder().encode(chunkType)
   const keywordBytes = new TextEncoder().encode(keyword)
-  const contentBytes = new TextEncoder().encode(content)
+  const contentBytes =
+    content instanceof Uint8Array ? content : new TextEncoder().encode(content)
 
   let chunkData: Uint8Array
   if (chunkType === 'iTXt') {
@@ -66,12 +73,11 @@ function createPngWithChunk(
   new DataView(lengthBytes.buffer).setUint32(0, chunkData.length, false)
 
   const crc = new Uint8Array(4)
-
   const iendType = new TextEncoder().encode('IEND')
   const iendLength = new Uint8Array(4)
   const iendCrc = new Uint8Array(4)
 
-  const total = signature.length + 4 + 4 + chunkData.length + 4 + 4 + 4 + 0 + 4
+  const total = signature.length + (4 + 4 + chunkData.length + 4) + (4 + 4 + 4)
   const result = new Uint8Array(total)
 
   let offset = 0
@@ -138,6 +144,21 @@ describe('getFromPngBuffer', () => {
     expect(result['workflow']).toBe(workflow)
   })
 
+  it('logs warning and skips iTXt chunk with unsupported compression method', async () => {
+    vi.spyOn(console, 'warn').mockImplementation(() => {})
+    const buffer = createPngWithChunk('iTXt', 'workflow', 'data', {
+      compressionFlag: 1,
+      compressionMethod: 99
+    })
+
+    const result = await getFromPngBuffer(buffer)
+
+    expect(result['workflow']).toBeUndefined()
+    expect(console.warn).toHaveBeenCalledWith(
+      expect.stringContaining('Unsupported compression method 99')
+    )
+  })
+
   it('parses compressed iTXt chunk', async () => {
     const workflow = '{"nodes":[{"id":1,"type":"KSampler"}]}'
     const contentBytes = new TextEncoder().encode(workflow)
@@ -163,83 +184,49 @@ describe('getFromPngBuffer', () => {
       pos += chunk.length
     }
 
-    const buffer = createPngWithCompressedITXt(
-      'workflow',
-      compressedBytes,
-      '',
-      ''
-    )
+    const buffer = createPngWithChunk('iTXt', 'workflow', compressedBytes, {
+      compressionFlag: 1,
+      compressionMethod: 0
+    })
     const result = await getFromPngBuffer(buffer)
     expect(result['workflow']).toBe(workflow)
   })
 })
 
-function createPngWithCompressedITXt(
-  keyword: string,
-  compressedContent: Uint8Array,
-  languageTag: string,
-  translatedKeyword: string
-): ArrayBuffer {
-  const signature = new Uint8Array([
-    0x89, 0x50, 0x4e, 0x47, 0x0d, 0x0a, 0x1a, 0x0a
-  ])
-  const typeBytes = new TextEncoder().encode('iTXt')
-  const keywordBytes = new TextEncoder().encode(keyword)
-  const langBytes = new TextEncoder().encode(languageTag)
-  const transBytes = new TextEncoder().encode(translatedKeyword)
+describe('getFromPngFile', () => {
+  it('reads metadata from a File object', async () => {
+    const workflow = '{"nodes":[]}'
+    const buffer = createPngWithChunk('tEXt', 'workflow', workflow)
+    const file = new File([buffer], 'test.png', { type: 'image/png' })
 
-  const totalLength =
-    keywordBytes.length +
-    1 +
-    2 +
-    langBytes.length +
-    1 +
-    transBytes.length +
-    1 +
-    compressedContent.length
+    const result = await getFromPngFile(file)
 
-  const chunkData = new Uint8Array(totalLength)
-  let pos = 0
-  chunkData.set(keywordBytes, pos)
-  pos += keywordBytes.length
-  chunkData[pos++] = 0
-  chunkData[pos++] = 1
-  chunkData[pos++] = 0
-  chunkData.set(langBytes, pos)
-  pos += langBytes.length
-  chunkData[pos++] = 0
-  chunkData.set(transBytes, pos)
-  pos += transBytes.length
-  chunkData[pos++] = 0
-  chunkData.set(compressedContent, pos)
+    expect(result['workflow']).toBe(workflow)
+  })
 
-  const lengthBytes = new Uint8Array(4)
-  new DataView(lengthBytes.buffer).setUint32(0, chunkData.length, false)
+  it('returns empty for an invalid PNG File', async () => {
+    vi.spyOn(console, 'error').mockImplementation(() => {})
+    const file = new File([new ArrayBuffer(8)], 'bad.png', {
+      type: 'image/png'
+    })
 
-  const crc = new Uint8Array(4)
-  const iendType = new TextEncoder().encode('IEND')
-  const iendLength = new Uint8Array(4)
-  const iendCrc = new Uint8Array(4)
+    const result = await getFromPngFile(file)
 
-  const total = signature.length + 4 + 4 + chunkData.length + 4 + 4 + 4 + 0 + 4
-  const result = new Uint8Array(total)
+    expect(result).toEqual({})
+    expect(console.error).toHaveBeenCalledWith('Not a valid PNG file')
+  })
 
-  let offset = 0
-  result.set(signature, offset)
-  offset += signature.length
-  result.set(lengthBytes, offset)
-  offset += 4
-  result.set(typeBytes, offset)
-  offset += 4
-  result.set(chunkData, offset)
-  offset += chunkData.length
-  result.set(crc, offset)
-  offset += 4
-  result.set(iendLength, offset)
-  offset += 4
-  result.set(iendType, offset)
-  offset += 4
-  result.set(iendCrc, offset)
+  describe('FileReader failure modes', () => {
+    const file = new File([new Uint8Array(16)], 'test.png')
 
-  return result.buffer
-}
+    it('rejects when the FileReader fires error', async () => {
+      mockFileReaderError('readAsArrayBuffer')
+      await expect(getFromPngFile(file)).rejects.toBeDefined()
+    })
+
+    it('rejects when the FileReader fires abort', async () => {
+      mockFileReaderAbort('readAsArrayBuffer')
+      await expect(getFromPngFile(file)).rejects.toThrow('FileReader aborted')
+    })
+  })
+})

src/scripts/metadata/png.ts

@@ -126,6 +126,7 @@ export async function getFromPngFile(
       resolve(result)
     }
     reader.onerror = () => reject(reader.error)
+    reader.onabort = () => reject(new Error('FileReader aborted'))
     reader.readAsArrayBuffer(file)
   })
 }

src/scripts/metadata/svg.test.ts

@@ -0,0 +1,42 @@
+import { describe, expect, it } from 'vitest'
+
+import { getSvgMetadata } from './svg'
+
+function svgFile(content: string): File {
+  return new File([content], 'test.svg', { type: 'image/svg+xml' })
+}
+
+describe('getSvgMetadata', () => {
+  it('extracts workflow and prompt from CDATA in <metadata>', async () => {
+    const svg = `<svg xmlns="http://www.w3.org/2000/svg">
+      <metadata><![CDATA[${JSON.stringify({
+        workflow: { nodes: [] },
+        prompt: { '1': {} }
+      })}]]></metadata>
+      <rect width="1" height="1"/>
+    </svg>`
+
+    const result = await getSvgMetadata(svgFile(svg))
+
+    expect(result).toEqual({
+      workflow: { nodes: [] },
+      prompt: { '1': {} }
+    })
+  })
+
+  it('returns empty when SVG has no metadata element', async () => {
+    const svg = '<svg xmlns="http://www.w3.org/2000/svg"><rect/></svg>'
+
+    const result = await getSvgMetadata(svgFile(svg))
+
+    expect(result).toEqual({})
+  })
+
+  it('returns empty when CDATA contains invalid JSON', async () => {
+    const svg = `<svg><metadata><![CDATA[not valid json]]></metadata></svg>`
+
+    const result = await getSvgMetadata(svgFile(svg))
+
+    expect(result).toEqual({})
+  })
+})

src/scripts/pnginfo.test.ts

@@ -1,4 +1,6 @@
-import { describe, expect, it, vi } from 'vitest'
+import fs from 'fs'
+import path from 'path'
+import { afterEach, describe, expect, it, vi } from 'vitest'
 
 import { getFromAvifFile } from './metadata/avif'
 import { getFromFlacFile } from './metadata/flac'
@@ -21,67 +23,183 @@ vi.mock('./metadata/avif', () => ({
   getFromAvifFile: vi.fn()
 }))
 
-function buildExifPayload(workflowJson: string): Uint8Array {
-  const fullStr = `workflow:${workflowJson}\0`
-  const strBytes = new TextEncoder().encode(fullStr)
+afterEach(() => vi.restoreAllMocks())
 
-  const headerSize = 22
-  const buf = new Uint8Array(headerSize + strBytes.length)
+const fixturesDir = path.resolve(__dirname, 'metadata/__fixtures__')
+
+type AsciiIfdEntry = { tag: number; value: string }
+
+function encodeAsciiIfd(entries: AsciiIfdEntry[]): Uint8Array {
+  const tableSize = 10 + 12 * entries.length
+  const strings = entries.map((e) => new TextEncoder().encode(`${e.value}\0`))
+  const totalStringBytes = strings.reduce((sum, s) => sum + s.length, 0)
+
+  const buf = new Uint8Array(tableSize + totalStringBytes)
   const dv = new DataView(buf.buffer)
 
   buf.set([0x49, 0x49], 0)
   dv.setUint16(2, 0x002a, true)
   dv.setUint32(4, 8, true)
-  dv.setUint16(8, 1, true)
-  dv.setUint16(10, 0, true)
-  dv.setUint16(12, 2, true)
-  dv.setUint32(14, strBytes.length, true)
-  dv.setUint32(18, 22, true)
-  buf.set(strBytes, 22)
+  dv.setUint16(8, entries.length, true)
+
+  let stringOffset = tableSize
+  for (let i = 0; i < entries.length; i++) {
+    const entryOffset = 10 + i * 12
+    dv.setUint16(entryOffset, entries[i].tag, true)
+    dv.setUint16(entryOffset + 2, 2, true)
+    dv.setUint32(entryOffset + 4, strings[i].length, true)
+    dv.setUint32(entryOffset + 8, stringOffset, true)
+    buf.set(strings[i], stringOffset)
+    stringOffset += strings[i].length
+  }
 
   return buf
 }
 
-function buildWebp(precedingChunkLength: number, workflowJson: string): File {
-  const exifPayload = buildExifPayload(workflowJson)
-  const precedingPadded = precedingChunkLength + (precedingChunkLength % 2)
-  const totalSize = 12 + (8 + precedingPadded) + (8 + exifPayload.length)
+type WebpChunk = { type: string; payload: Uint8Array }
 
-  const buffer = new Uint8Array(totalSize)
-  const dv = new DataView(buffer.buffer)
+function wrapInWebp(chunks: WebpChunk[]): File {
+  let payloadSize = 0
+  for (const c of chunks) {
+    payloadSize += 8 + c.payload.length + (c.payload.length % 2)
+  }
+  const totalSize = 12 + payloadSize
+  const buf = new Uint8Array(totalSize)
+  const dv = new DataView(buf.buffer)
 
-  buffer.set([0x52, 0x49, 0x46, 0x46], 0)
+  buf.set([0x52, 0x49, 0x46, 0x46], 0)
   dv.setUint32(4, totalSize - 8, true)
-  buffer.set([0x57, 0x45, 0x42, 0x50], 8)
+  buf.set([0x57, 0x45, 0x42, 0x50], 8)
 
-  buffer.set([0x56, 0x50, 0x38, 0x20], 12)
-  dv.setUint32(16, precedingChunkLength, true)
+  let offset = 12
+  for (const c of chunks) {
+    for (let i = 0; i < 4; i++) {
+      buf[offset + i] = c.type.charCodeAt(i)
+    }
+    dv.setUint32(offset + 4, c.payload.length, true)
+    buf.set(c.payload, offset + 8)
+    offset += 8 + c.payload.length + (c.payload.length % 2)
+  }
 
-  const exifStart = 20 + precedingPadded
-  buffer.set([0x45, 0x58, 0x49, 0x46], exifStart)
-  dv.setUint32(exifStart + 4, exifPayload.length, true)
-  buffer.set(exifPayload, exifStart + 8)
+  return new File([buf], 'test.webp', { type: 'image/webp' })
+}
 
-  return new File([buffer], 'test.webp', { type: 'image/webp' })
+function exifChunk(
+  entries: AsciiIfdEntry[],
+  options: { withExifPrefix?: boolean } = {}
+): WebpChunk {
+  const ifd = encodeAsciiIfd(entries)
+  if (!options.withExifPrefix) {
+    return { type: 'EXIF', payload: ifd }
+  }
+  const prefixed = new Uint8Array(6 + ifd.length)
+  prefixed.set(new TextEncoder().encode('Exif\0\0'), 0)
+  prefixed.set(ifd, 6)
+  return { type: 'EXIF', payload: prefixed }
 }
 
 describe('getWebpMetadata', () => {
-  it('finds workflow when a preceding chunk has odd length (RIFF padding)', async () => {
-    const workflow = '{"nodes":[]}'
-    const file = buildWebp(3, workflow)
+  it('returns empty when the file is not a valid WEBP', async () => {
+    vi.spyOn(console, 'error').mockImplementation(() => {})
+    const file = new File([new Uint8Array(12)], 'fake.webp')
 
     const metadata = await getWebpMetadata(file)
 
-    expect(metadata.workflow).toBe(workflow)
+    expect(metadata).toEqual({})
+    expect(console.error).toHaveBeenCalledWith('Not a valid WEBP file')
   })
 
-  it('finds workflow when preceding chunk has even length (no padding)', async () => {
-    const workflow = '{"nodes":[1]}'
-    const file = buildWebp(4, workflow)
+  it('returns empty when a valid WEBP has no EXIF chunk', async () => {
+    const file = wrapInWebp([
+      { type: 'VP8 ', payload: new Uint8Array([0, 0, 0, 0]) }
+    ])
 
     const metadata = await getWebpMetadata(file)
 
-    expect(metadata.workflow).toBe(workflow)
+    expect(metadata).toEqual({})
+  })
+
+  it('extracts workflow and prompt from EXIF without prefix', async () => {
+    const bytes = fs.readFileSync(path.join(fixturesDir, 'with_metadata.webp'))
+    const file = new File([bytes], 'test.webp', { type: 'image/webp' })
+
+    const metadata = await getWebpMetadata(file)
+
+    expect(metadata).toEqual({
+      workflow:
+        '{"nodes":[{"id":1,"type":"KSampler","pos":[100,100],"size":[200,200]}]}',
+      prompt: '{"1":{"class_type":"KSampler","inputs":{}}}'
+    })
+  })
+
+  it('extracts workflow and prompt from EXIF with Exif\\0\\0 prefix', async () => {
+    const bytes = fs.readFileSync(
+      path.join(fixturesDir, 'with_metadata_exif_prefix.webp')
+    )
+    const file = new File([bytes], 'test.webp', { type: 'image/webp' })
+
+    const metadata = await getWebpMetadata(file)
+
+    expect(metadata).toEqual({
+      workflow:
+        '{"nodes":[{"id":1,"type":"KSampler","pos":[100,100],"size":[200,200]}]}',
+      prompt: '{"1":{"class_type":"KSampler","inputs":{}}}'
+    })
+  })
+
+  it('walks past odd-length preceding chunks (RIFF padding)', async () => {
+    const file = wrapInWebp([
+      { type: 'VP8 ', payload: new Uint8Array(3) },
+      exifChunk([{ tag: 0, value: 'workflow:{"a":1}' }])
+    ])
+
+    const metadata = await getWebpMetadata(file)
+
+    expect(metadata).toEqual({ workflow: '{"a":1}' })
+  })
+})
+
+describe('getLatentMetadata', () => {
+  function buildSafetensors(headerObj: object): File {
+    const headerBytes = new TextEncoder().encode(JSON.stringify(headerObj))
+    const buf = new Uint8Array(8 + headerBytes.length)
+    const dv = new DataView(buf.buffer)
+    dv.setUint32(0, headerBytes.length, true)
+    dv.setUint32(4, 0, true)
+    buf.set(headerBytes, 8)
+    return new File([buf], 'test.safetensors')
+  }
+
+  it('extracts __metadata__ from a safetensors header', async () => {
+    const workflow =
+      '{"nodes":[{"id":1,"type":"KSampler","pos":[100,100],"size":[200,200]}]}'
+    const prompt = '{"1":{"class_type":"KSampler","inputs":{}}}'
+    const file = buildSafetensors({
+      __metadata__: { workflow, prompt },
+      'tensor.weight': { dtype: 'F32', shape: [1], data_offsets: [0, 4] }
+    })
+
+    const metadata = await getLatentMetadata(file)
+
+    expect(metadata).toEqual({ workflow, prompt })
+  })
+
+  it('returns undefined when the safetensors header has no __metadata__', async () => {
+    const file = buildSafetensors({
+      'tensor.weight': { dtype: 'F32', shape: [1], data_offsets: [0, 4] }
+    })
+
+    const metadata = await getLatentMetadata(file)
+
+    expect(metadata).toBeUndefined()
+  })
+
+  it('returns undefined for a truncated or malformed file', async () => {
+    const file = new File([new Uint8Array(4)], 'bad.safetensors')
+
+    const metadata = await getLatentMetadata(file)
+
+    expect(metadata).toBeUndefined()
   })
 })
 
@@ -116,37 +234,3 @@ describe('format-specific metadata wrappers', () => {
     expect(result).toEqual({ workflow: '{"avif":1}' })
   })
 })
-
-const buildSafetensors = (header: Record<string, unknown>): File => {
-  const headerJson = JSON.stringify(header)
-  const headerBytes = new TextEncoder().encode(headerJson)
-  const buf = new ArrayBuffer(8 + headerBytes.length)
-  const dv = new DataView(buf)
-  dv.setUint32(0, headerBytes.length, true)
-  dv.setUint32(4, 0, true)
-  new Uint8Array(buf, 8).set(headerBytes)
-  return new File([buf], 'x.safetensors')
-}
-
-describe('getLatentMetadata', () => {
-  it('returns the __metadata__ object from a safetensors header', async () => {
-    const file = buildSafetensors({
-      __metadata__: { workflow: '{"nodes":[]}', extra: 'value' },
-      'tensor.weight': { dtype: 'F32', shape: [1], data_offsets: [0, 4] }
-    })
-
-    const result = await getLatentMetadata(file)
-
-    expect(result).toEqual({ workflow: '{"nodes":[]}', extra: 'value' })
-  })
-
-  it('resolves undefined when header has no __metadata__ entry', async () => {
-    const file = buildSafetensors({
-      'tensor.weight': { dtype: 'F32', shape: [1], data_offsets: [0, 4] }
-    })
-
-    const result = await getLatentMetadata(file)
-
-    expect(result).toBeUndefined()
-  })
-})

src/scripts/pnginfo.ts

@@ -105,14 +105,17 @@ export function getWebpMetadata(file: File) {
           ...webp.slice(offset, offset + 4)
         )
         if (chunk_type === 'EXIF') {
+          let exifOffset = offset + 8
+          let exifLength = chunk_length
           if (
-            String.fromCharCode(...webp.slice(offset + 8, offset + 8 + 6)) ==
+            String.fromCharCode(...webp.slice(exifOffset, exifOffset + 6)) ==
             'Exif\0\0'
           ) {
-            offset += 6
+            exifOffset += 6
+            exifLength -= 6
           }
-          let data = parseExifData(
-            webp.slice(offset + 8, offset + 8 + chunk_length)
+          const data = parseExifData(
+            webp.slice(exifOffset, exifOffset + exifLength)
           )
           for (const key in data) {
             const value = data[Number(key)]
@@ -131,30 +134,38 @@ export function getWebpMetadata(file: File) {
 
       r(txt_chunks)
     }
-
+    reader.onerror = () => r({})
+    reader.onabort = () => r({})
     reader.readAsArrayBuffer(file)
   })
 }
 
-export function getLatentMetadata(file: File): Promise<Record<string, string>> {
+export function getLatentMetadata(
+  file: File
+): Promise<Record<string, string> | undefined> {
   return new Promise((r) => {
     const reader = new FileReader()
     reader.onload = (event) => {
-      const safetensorsData = new Uint8Array(
-        event.target?.result as ArrayBuffer
-      )
-      const dataView = new DataView(safetensorsData.buffer)
-      let header_size = dataView.getUint32(0, true)
-      let offset = 8
-      let header = JSON.parse(
-        new TextDecoder().decode(
-          safetensorsData.slice(offset, offset + header_size)
+      try {
+        const safetensorsData = new Uint8Array(
+          event.target?.result as ArrayBuffer
         )
-      )
-      r(header.__metadata__)
+        const dataView = new DataView(safetensorsData.buffer)
+        const headerSize = dataView.getUint32(0, true)
+        const offset = 8
+        const header = JSON.parse(
+          new TextDecoder().decode(
+            safetensorsData.slice(offset, offset + headerSize)
+          )
+        )
+        r(header.__metadata__)
+      } catch {
+        r(undefined)
+      }
     }
-
-    var slice = file.slice(0, 1024 * 1024 * 4)
+    reader.onerror = () => r(undefined)
+    reader.onabort = () => r(undefined)
+    const slice = file.slice(0, 1024 * 1024 * 4)
     reader.readAsArrayBuffer(slice)
   })
 }