Fix cyclic prototype errors with subgraphNodes (#5637)

#5024 added support for connecting primitive nodes to subgraph inputs.
To accomplish this, it pulls WidgetLocator information from the node
owning the widget.

This `node` property does not exist on all IBaseWidget. `toConcrete` was
used to instead have a BaseWidget which is guaranteed to have a node
property. The issue that was missed, is that a widget which lacks this
information (such as most implemented by custom nodes) sets the node
value to the argument which was passed. Here that is the reference to
the subgraph node. Sometimes, this `#setWidget` call is made multiple
times, and when this occurs, the `input.widget` has itself set as the
protoyep, throwing an error.

This is resolved by instead taking an additional input which is
unambiguous.

For reference, this is a near minimal workflow using comfy_mtb that
replicates the issue

[cyclic.json](https://github.com/user-attachments/files/22412187/cyclic.json)

Special thanks to @melMass for assistance discovering this issue.

┆Issue is synchronized with this [Notion
page](https://www.notion.so/PR-5637-Fix-cyclic-prototype-errors-with-subgraphNodes-2726d73d365081fea356f5197e4c2b42)
by [Unito](https://www.unito.io)

src/lib/litegraph/src/subgraph/SubgraphNode.ts

@@ -4,7 +4,10 @@ import type { LGraphCanvas } from '@/lib/litegraph/src/LGraphCanvas'
 import { LGraphNode } from '@/lib/litegraph/src/LGraphNode'
 import { LLink, type ResolvedConnection } from '@/lib/litegraph/src/LLink'
 import { RecursionError } from '@/lib/litegraph/src/infrastructure/RecursionError'
-import type { ISubgraphInput } from '@/lib/litegraph/src/interfaces'
+import type {
+  ISubgraphInput,
+  IWidgetLocator
+} from '@/lib/litegraph/src/interfaces'
 import type {
   INodeInputSlot,
   ISlotType,
@@ -78,9 +81,10 @@ export class SubgraphNode extends LGraphNode implements BaseLGraph {
         const existingInput = this.inputs.find((i) => i.name == name)
         if (existingInput) {
           const linkId = subgraphInput.linkIds[0]
-          const { inputNode } = subgraph.links[linkId].resolve(subgraph)
+          const { inputNode, input } = subgraph.links[linkId].resolve(subgraph)
           const widget = inputNode?.widgets?.find?.((w) => w.name == name)
-          if (widget) this.#setWidget(subgraphInput, existingInput, widget)
+          if (widget)
+            this.#setWidget(subgraphInput, existingInput, widget, input?.widget)
           return
         }
         const input = this.addInput(name, type)
@@ -185,13 +189,14 @@ export class SubgraphNode extends LGraphNode implements BaseLGraph {
 
     subgraphInput.events.addEventListener(
       'input-connected',
-      () => {
+      (e) => {
         if (input._widget) return
 
         const widget = subgraphInput._widget
         if (!widget) return
 
-        this.#setWidget(subgraphInput, input, widget)
+        const widgetLocator = e.detail.input.widget
+        this.#setWidget(subgraphInput, input, widget, widgetLocator)
       },
       { signal }
     )
@@ -301,7 +306,7 @@ export class SubgraphNode extends LGraphNode implements BaseLGraph {
         const widget = resolved.inputNode.getWidgetFromSlot(resolved.input)
         if (!widget) continue
 
-        this.#setWidget(subgraphInput, input, widget)
+        this.#setWidget(subgraphInput, input, widget, resolved.input.widget)
         break
       }
     }
@@ -310,11 +315,13 @@ export class SubgraphNode extends LGraphNode implements BaseLGraph {
   #setWidget(
     subgraphInput: Readonly<SubgraphInput>,
     input: INodeInputSlot,
-    widget: Readonly<IBaseWidget>
+    widget: Readonly<IBaseWidget>,
+    inputWidget: IWidgetLocator | undefined
   ) {
     // Use the first matching widget
-    const targetWidget = toConcreteWidget(widget, this)
-    const promotedWidget = targetWidget.createCopyForNode(this)
+    const promotedWidget = toConcreteWidget(widget, this).createCopyForNode(
+      this
+    )
 
     Object.assign(promotedWidget, {
       get name() {
@@ -372,11 +379,9 @@ export class SubgraphNode extends LGraphNode implements BaseLGraph {
     // NOTE: This code creates linked chains of prototypes for passing across
     // multiple levels of subgraphs. As part of this, it intentionally avoids
     // creating new objects. Have care when making changes.
-    const backingInput =
-      targetWidget.node.findInputSlot(widget.name, true)?.widget ?? {}
     input.widget ??= { name: subgraphInput.name }
     input.widget.name = subgraphInput.name
-    Object.setPrototypeOf(input.widget, backingInput)
+    if (inputWidget) Object.setPrototypeOf(input.widget, inputWidget)
 
     input._widget = promotedWidget
   }