fix: handle failed global subgraph blueprint loading gracefully (#9063)

## Summary

Fix "Failed to load subgraph blueprints Error: [ASSERT] Workflow content
should be loaded" error occurring on cloud.

## Changes

- **What**: `getGlobalSubgraphData` now throws on API failure instead of
returning empty string, global blueprint data is validated before
loading, and individual global blueprint errors are properly propagated
to the toast/console reporting instead of being silently swallowed.

## Review Focus

Two root causes were fixed:
1. `getGlobalSubgraphData` returned `""` on failure — this empty string
was set as `originalContent`, which is falsy, triggering the assertion
in `ComfyWorkflow.load()`.
2. `loadInstalledBlueprints` used an internal `Promise.allSettled` whose
results were discarded, so individual global blueprint failures never
reached the error reporting in `fetchSubgraphs`.

Fixes COM-15199

┆Issue is synchronized with this [Notion
page](https://www.notion.so/PR-9063-fix-handle-failed-global-subgraph-blueprint-loading-gracefully-30e6d73d3650818d9cc8ecf81cd0264e)
by [Unito](https://www.unito.io)

src/stores/subgraphStore.test.ts

@@ -225,6 +225,68 @@ describe('useSubgraphStore', () => {
     })
   })
 
+  it('should handle global blueprint with empty data gracefully', async () => {
+    const consoleSpy = vi.spyOn(console, 'error').mockImplementation(() => {})
+    await mockFetch(
+      {},
+      {
+        broken_blueprint: {
+          name: 'Broken Blueprint',
+          info: { node_pack: 'test_pack' },
+          data: ''
+        }
+      }
+    )
+    expect(consoleSpy).toHaveBeenCalledWith(
+      'Failed to load subgraph blueprint',
+      expect.any(Error)
+    )
+    expect(store.subgraphBlueprints).toHaveLength(0)
+    consoleSpy.mockRestore()
+  })
+
+  it('should handle global blueprint with rejected data promise gracefully', async () => {
+    const consoleSpy = vi.spyOn(console, 'error').mockImplementation(() => {})
+    await mockFetch(
+      {},
+      {
+        failing_blueprint: {
+          name: 'Failing Blueprint',
+          info: { node_pack: 'test_pack' },
+          data: Promise.reject(new Error('Network error')) as unknown as string
+        }
+      }
+    )
+    expect(consoleSpy).toHaveBeenCalledWith(
+      'Failed to load subgraph blueprint',
+      expect.any(Error)
+    )
+    expect(store.subgraphBlueprints).toHaveLength(0)
+    consoleSpy.mockRestore()
+  })
+
+  it('should load valid global blueprints even when others fail', async () => {
+    const consoleSpy = vi.spyOn(console, 'error').mockImplementation(() => {})
+    await mockFetch(
+      {},
+      {
+        broken: {
+          name: 'Broken',
+          info: { node_pack: 'test_pack' },
+          data: ''
+        },
+        valid: {
+          name: 'Valid Blueprint',
+          info: { node_pack: 'test_pack' },
+          data: JSON.stringify(mockGraph)
+        }
+      }
+    )
+    expect(consoleSpy).toHaveBeenCalled()
+    expect(store.subgraphBlueprints).toHaveLength(1)
+    consoleSpy.mockRestore()
+  })
+
   describe('search_aliases support', () => {
     it('should include search_aliases from workflow extra', async () => {
       const mockGraphWithAliases = {

src/stores/subgraphStore.ts

@@ -198,13 +198,19 @@ export const useSubgraphStore = defineStore('subgraph', () => {
     }
     async function loadInstalledBlueprints() {
       async function loadGlobalBlueprint([k, v]: [string, GlobalSubgraphData]) {
+        const data = await v.data
+        if (typeof data !== 'string' || data.trim().length === 0) {
+          throw new Error(
+            `Global blueprint '${v.name}' (${k}) returned empty content`
+          )
+        }
         const path = SubgraphBlueprint.basePath + v.name + '.json'
         const blueprint = new SubgraphBlueprint({
           path,
           modified: Date.now(),
           size: -1
         })
-        blueprint.originalContent = blueprint.content = await v.data
+        blueprint.originalContent = blueprint.content = data
         blueprint.filename = v.name
         useWorkflowStore().attachWorkflow(blueprint)
         const loaded = await blueprint.load()
@@ -238,16 +244,19 @@ export const useSubgraphStore = defineStore('subgraph', () => {
           return false
         return true
       })
-      await Promise.allSettled(filteredEntries.map(loadGlobalBlueprint))
+      return Promise.allSettled(filteredEntries.map(loadGlobalBlueprint))
     }
 
     const userSubs = (
       await api.listUserDataFullInfo(SubgraphBlueprint.basePath)
     ).filter((f) => f.path.endsWith('.json'))
-    const settled = await Promise.allSettled([
-      ...userSubs.map(loadBlueprint),
-      loadInstalledBlueprints()
+    const [globalResult, ...userResults] = await Promise.allSettled([
+      loadInstalledBlueprints(),
+      ...userSubs.map(loadBlueprint)
     ])
+    const globalResults =
+      globalResult.status === 'fulfilled' ? globalResult.value : []
+    const settled = [...globalResults, ...userResults]
 
     const errors = settled.filter((i) => 'reason' in i).map((i) => i.reason)
     errors.forEach((e) => console.error('Failed to load subgraph blueprint', e))