TSServer crash "Cannot read properties of undefined (reading 'sourceFile')" when switching between files in different projects

Type: Bug

Typescript server is frequently crashing when opening files in different TS projects

Repro:
Have multiple files in different typescript projects (ex. a/tsconfig.json, b/tsconfig.json, c/tsconfig.json). Use "jump to definition" from a file in project "a" to files in the other projects quickly, observe tsserver crashed with code "SIGTERM" (not "SIGABRT" from memory issues) with a message "Cannot read properties of undefined (reading 'sourceFile')".

Note: I found https://github.com/microsoft/vscode/issues/229335 reporting this, but there didn't seem to be any resolution there. Happy to provide any followup logs / information to get this fully tracked down this time. I found this stack trace in the error logs consistently:

    Cannot read properties of undefined (reading 'sourceFile')

    TypeError: Cannot read properties of undefined (reading 'sourceFile')
        at isDocumentRegistryEntry (/Applications/VSCode.app/Contents/Resources/app/extensions/node_modules/typescript/lib/typescript.js:143850:18)
        at getDocumentRegistryEntry (/Applications/VSCode.app/Contents/Resources/app/extensions/node_modules/typescript/lib/typescript.js:143926:19)
        at Object.releaseDocumentWithKey (/Applications/VSCode.app/Contents/Resources/app/extensions/node_modules/typescript/lib/typescript.js:144021:19)
        at /Applications/VSCode.app/Contents/Resources/app/extensions/node_modules/typescript/lib/typescript.js:152976:65
        at forEach (/Applications/VSCode.app/Contents/Resources/app/extensions/node_modules/typescript/lib/typescript.js:2305:22)
        at cleanupSemanticCache (/Applications/VSCode.app/Contents/Resources/app/extensions/node_modules/typescript/lib/typescript.js:152976:7)
        at Object.dispose (/Applications/VSCode.app/Contents/Resources/app/extensions/node_modules/typescript/lib/typescript.js:152981:5)
        at ConfiguredProject2.close (/Applications/VSCode.app/Contents/Resources/app/extensions/node_modules/typescript/lib/typescript.js:187714:26)
        at ConfiguredProject2.close (/Applications/VSCode.app/Contents/Resources/app/extensions/node_modules/typescript/lib/typescript.js:189310:11)
        at _ProjectService.removeProject (/Applications/VSCode.app/Contents/Resources/app/extensions/node_modules/typescript/lib/typescript.js:190623:13)
        at /Applications/VSCode.app/Contents/Resources/app/extensions/node_modules/typescript/lib/typescript.js:192613:33
        at Set.forEach (<anonymous>)
        at _ProjectService.cleanupConfiguredProjects (/Applications/VSCode.app/Contents/Resources/app/extensions/node_modules/typescript/lib/typescript.js:192613:7)
        at _ProjectService.cleanupProjectsAndScriptInfos (/Applications/VSCode.app/Contents/Resources/app/extensions/node_modules/typescript/lib/typescript.js:192616:10)
        at _ProjectService.applyChangesInOpenFiles (/Applications/VSCode.app/Contents/Resources/app/extensions/node_modules/typescript/lib/typescript.js:192864:12)
        at updateOpen (/Applications/VSCode.app/Contents/Resources/app/extensions/node_modules/typescript/lib/typescript.js:194084:29)
        at /Applications/VSCode.app/Contents/Resources/app/extensions/node_modules/typescript/lib/typescript.js:196809:15
        at IOSession.executeWithRequestId (/Applications/VSCode.app/Contents/Resources/app/extensions/node_modules/typescript/lib/typescript.js:196798:14)
        at IOSession.executeCommand (/Applications/VSCode.app/Contents/Resources/app/extensions/node_modules/typescript/lib/typescript.js:196807:29)
        at IOSession.onMessage (/Applications/VSCode.app/Contents/Resources/app/extensions/node_modules/typescript/lib/typescript.js:196855:68)
        at Interface.<anonymous> (/Applications/VSCode.app/Contents/Resources/app/extensions/node_modules/typescript/lib/_tsserver.js:495:14)
        at Interface.emit (node:events:513:28)
        at [_onLine] [as _onLine] (node:internal/readline/interface:416:12)
        at [_normalWrite] [as _normalWrite] (node:internal/readline/interface:610:22)
        at Socket.ondata (node:internal/readline/interface:243:23)
        at Socket.emit (node:events:513:28)
        at addChunk (node:internal/streams/readable:559:12)
        at readableAddChunkPushByteMode (node:internal/streams/readable:510:3)
        at Readable.push (node:internal/streams/readable:390:5)
        at Pipe.onStreamRead (node:internal/stream_base_commons:189:23)

with the exit message:

2025-09-04 12:27:19.232 [info] Killing TS Server
2025-09-04 12:27:19.429 [error] TSServer exited. Code: null. Signal: SIGTERM

It definitely feels like some race condition when multiple projects are being opened/closed repeatedly. I'm able to repro it pretty consistently in my monorepo by spamming "going to definition" with the repro above, but it seems to happen often in practice too (or at least our TSServer crashes very often, assuming this repro could be related)

VS Code version: Code - Insiders 1.104.0-insider (Universal) (2617e6ca1619162fd9052c2cabba1d741eb722b8, 2025-09-04T09:27:45.417Z)
OS version: Darwin arm64 24.6.0
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