Avoid TypeError in ObservableGit when gitApi.repositories is transiently nullish

[Copilot]

Telemetry reports an unhandled TypeError: e is not iterable originating from ArrayMap.setItems inside mapObservableArrayCached. The minified stack (BOe.setItems ← Wd._computeFn ← recomputeInitiallyAndOnChange ← init) maps to ObservableGit.init in the Copilot Chat extension. Although the typing chain is fully non-null (mapObservableArrayCached takes IObservable<readonly TIn[]>, and repos is built from gitApi.repositories typed Repository[]), the git extension API can transiently return undefined from its repositories getter (e.g. during extension reload), violating its own type contract and propagating a nullish value into ArrayMap.setItems's for...of loop.

Description

• extensions/copilot/src/platform/inlineEdits/common/observableGit.ts — coerce a nullish gitApi.repositories to [] at the boundary where the git extension API is consumed. This is the actual point in the chain where reality diverges from the declared typing, so the guard belongs here rather than in the generic observable utility.

const repos = observableFromEvent(this, (e) => gitApi.onDidOpenRepository(e), () => gitApi.repositories ?? []);

The generic mapObservableArrayCached utility is left unchanged, preserving its readonly TIn[] contract so future violations elsewhere are not silently masked.

[bryanchen-d]

@copilot why not fix it in extensions/copilot/src/platform/inlineEdits/common/observableGit.ts? what's the typing of items.read() returns? I think we should fix the typing if anywhere in the chain of flow that assign an nullish value while it is not supposed to be null by typing

[Copilot]

@copilot why not fix it in extensions/copilot/src/platform/inlineEdits/common/observableGit.ts? what's the typing of items.read() returns? I think we should fix the typing if anywhere in the chain of ...

Good point — moved the fix into observableGit.ts and reverted the generic mapObservableArrayCached change in 0c88a1f.

The typing chain is all non-null: mapObservableArrayCached takes IObservable<readonly TIn[]>, repos is built from gitApi.repositories which is typed Repository[]. The runtime nullish must therefore originate from the git extension's repositories getter returning undefined in some transient state (e.g. extension reloading), violating its own type contract. I can't fix the upstream git.d.ts typing without making every consumer handle nullish, so I added ?? [] at the boundary where we consume that API.

[Copilot]

Pull request overview

This PR hardens Copilot Chat’s ObservableGit initialization against a real-world Git extension API contract violation where gitApi.repositories can be transiently undefined, preventing a TypeError: e is not iterable from propagating into mapObservableArrayCached/ArrayMap.setItems.

Changes:

• Coerce gitApi.repositories to [] at the Git API consumption boundary in ObservableGit.init.

Show a summary per file

File	Description
extensions/copilot/src/platform/inlineEdits/common/observableGit.ts	Guards against transiently nullish gitApi.repositories by defaulting to an empty array when creating the repos observable.

Copilot's findings

• Files reviewed: 1/1 changed files
• Comments generated: 1