[Error] a.getId is not a function — explorerView / asyncDataTree

[vs-code-engineering]

Error Message

unhandlederror-a.getId is not a function

Stack Trace

    at Object.getId (./src/vs/workbench/contrib/files/browser/views/explorerView.ts:92:0)
    at Ey.getDataNode (./src/vs/base/browser/ui/tree/asyncDataTree.ts:1067:0)
    at Ey._updateChildren (./src/vs/base/browser/ui/tree/asyncDataTree.ts:822:0)
    at async Ey.updateChildren (./src/vs/base/browser/ui/tree/asyncDataTree.ts:799:0)

Raw Stack Trace (minified)

TypeError: a.getId is not a function     at Object.getId (out/vs/sessions/sessions.desktop.main.js:2215:33334)     at Ey.getDataNode (out/vs/sessions/sessions.desktop.main.js:861:37507)     at Ey._updateChildren (out/vs/sessions/sessions.desktop.main.js:861:33915)     at async Ey.updateChildren (out/vs/sessions/sessions.desktop.main.js:861:33429)

Details

Property	Value
Bucket ID	2d5fb167-0093-479f-0664-6bf4e416efd2
Version	1.117.0-insider
Commit	a947515f
Last Seen	Sun Apr 19 2026 23:43:16 GMT+0000 (Coordinated Universal Time)
Platforms	Linux, Windows, Mac
Product	Agents

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This issue was automatically created from the VS Code Errors Dashboard

[vs-code-engineering]

Regression Details

• Product: Agents
• Regression type: New error
• Last release without this error: 1.116.0-insider (5272631e)
• First release with this error: 1.116.0-insider (ae130017)
• Commit range: 5272631e...ae130017

Deminified Stack (key frames)

#	Source
1	explorerView.ts:92 — Object.getId
2	asyncDataTree.ts:1067 — getDataNode
3	asyncDataTree.ts:822 — _updateChildren
4	asyncDataTree.ts:799 — updateChildren

The getId delegate in the explorer view's tree data source is called with an element that does not implement the expected getId() method, causing a TypeError. This affects 12 users across all platforms on build a947515f (1.117.0-insider).

Generated by errors-agents-regression-scan · ◷

Generated by errors-agents-regression-scan · ● 9.7M · ◷

[vs-code-engineering]

🔍 Error Investigation

Summary

The error a.getId is not a function occurs in the File Explorer's identity provider when the async data tree's getDataNode() method tries to resolve an element that is no longer in the tree's internal nodes map. This is caused by a race condition between _updateChildren() and setInput() in AsyncDataTree — during the async gap in _updateChildren (awaiting root.refreshPromise), the tree's root element can be replaced by a concurrent setInput() call. The stale element then fails lookup and the error-reporting path crashes when calling getId() on an element that may be an ExplorerItem[] array (which has no getId method). This disproportionately affects the Agents product because agent sessions frequently change workspace roots (creating worktrees, switching branches), increasing the likelihood of this race.

Culprit Commit

No specific culprit commit was identified. The regression range 5272631e...ae130017 contains 9 commits — all are cherry-picks (AI customization UX, onboarding, display fixes, license updates) that do not modify the explorer or async data tree code. This is a latent race condition in asyncDataTree.getDataNode() that manifests more frequently in the Agents product due to more frequent workspace root changes triggered by agent sessions.

Code Flow

sequenceDiagram
    participant ES as ExplorerService
    participant EV as ExplorerView.refresh()
    participant ADT as AsyncDataTree._updateChildren()
    participant GDN as AsyncDataTree.getDataNode()
    participant IP as identityProvider.getId()

    Note over ES: onDidChangeRoots / onDidChangeFocus
    ES->>EV: refresh(true) [no specific item]
    EV->>EV: toRefresh = tree.getInput() → ExplorerItem[] A
    EV->>ADT: updateChildren(A)
    ADT->>ADT: await root.refreshPromise
    Note over ADT: ⚠️ Root cause: during await,<br/>setInput(B) changes root.element
    ADT->>GDN: getDataNode(A)
    Note over GDN: A !== this.root.element (now B)<br/>nodes.get(A) → undefined
    GDN->>IP: getId(A as ExplorerItem)
    Note over IP: 💥 A is ExplorerItem[] array<br/>array.getId is not a function

Loading

Affected Files

File	Role
src/vs/base/browser/ui/tree/asyncDataTree.ts	Root cause — getDataNode() (line 1063-1072) uses stale element after async gap; error-reporting path calls getId() without type guard
src/vs/workbench/contrib/files/browser/views/explorerView.ts	Crash site — identityProvider.getId() (line 86-94) assumes stat is always an ExplorerItem
src/vs/workbench/contrib/files/browser/explorerService.ts	Trigger — concurrent refresh() and setTreeInput() calls from event handlers (lines 128-136)

Repro Steps

This is a race condition that is non-deterministic. To increase the likelihood:

1. Open VS Code Agents (or configure a multi-root workspace)
2. Start an agent session that creates a worktree or changes workspace roots
3. While the workspace root change is processing (setTreeInput → tree.setInput is in-flight), trigger a file explorer refresh (e.g., Alt-Tab away and back to trigger onDidChangeFocus, or have a file watcher fire)
4. The race between setInput() changing the root element and _updateChildren() using a stale reference triggers the error

Fix Proposal

Two complementary fixes are recommended:

Fix 1 (defensive) — asyncDataTree.ts → getDataNode()
Add a guard in the error-reporting path at line 1067 to handle cases where the element doesn't have getId. Wrap the identityProvider?.getId(element as T) call in a try-catch or check typeof (element as any).getId === 'function' before calling. This prevents the secondary crash and allows the more informative TreeError to be thrown instead.

Fix 2 (root cause) — asyncDataTree.ts → _updateChildren()
After the await at lines 817-819, re-validate the element. If element was the old root element and this.root.element has changed, either bail out (the input changed, so this refresh is stale) or re-resolve element to the new root. For example:

if (element !== this.root.element && !this.nodes.has(element as T)) {
    return; // element is stale after concurrent setInput
}

Fix location: src/vs/base/browser/ui/tree/asyncDataTree.ts → getDataNode() and _updateChildren()

Recommended Owner

@lramos15 — Explorer area owner per working-areas.md

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