`lang="js"` and `js/ts.preferGoToSourceDefinition` co-usage triggers tsserver debug failure

[x0rsw1tch]

Vue - Official extension or vue-tsc version

3.3.1 / 6.0.3

VSCode version

1.120.0

Vue version

3.5.34

TypeScript version

6.0.3

System Info

System:
    OS: Windows 11 10.0.22631
    CPU: (24) x64 AMD Ryzen 9 7900X 12-Core Processor
    Memory: 19.19 GB / 63.10 GB
  Binaries:
    Node: 24.13.0 - C:\Program Files\nodejs\node.EXE
    npm: 11.12.1 - C:\Program Files\nodejs\npm.CMD
    pnpm: 9.12.3 - C:\Users\tom\AppData\Local\pnpm\pnpm.EXE
  Browsers:
    Chrome: 147.0.7727.138
    Edge: Chromium (140.0.3485.54)
    Internet Explorer: 11.0.22621.3527

package.json dependencies

"dependencies": {
    "vue": "^3.5.32"
  },
  "devDependencies": {
    "@tsconfig/node24": "^24.0.4",
    "@types/node": "^24.12.2",
    "@vitejs/plugin-vue": "^6.0.6",
    "@vue/eslint-config-typescript": "^14.7.0",
    "@vue/tsconfig": "^0.9.1",
    "eslint": "^10.2.1",
    "eslint-config-prettier": "^10.1.8",
    "eslint-plugin-oxlint": "~1.60.0",
    "eslint-plugin-vue": "~10.8.0",
    "jiti": "^2.6.1",
    "npm-run-all2": "^8.0.4",
    "oxlint": "~1.60.0",
    "prettier": "3.8.3",
    "typescript": "~6.0.0",
    "vite": "^8.0.8",
    "vite-plugin-vue-devtools": "^8.1.1",
    "vue-tsc": "^3.2.6"
  },

Steps to reproduce

1. All extensions disabled, except Sublime text keymap, theme, and Vue (Official)
2. Use npm create vue@latest and create a blank project with TypeScript support
3. npm i
4. Convert /src/App.vue to use Options API (see linked repo)
5. Define a variable in the root app that will be passed to the
6. Create a child component that accepts a prop from the root app (see linked repo)
7. Add an instance of the child component in the root app (see linked repo)
8. Try to use "Go to Definition" on the component in the template, or the variable

What is expected?

Using "Go To Definition" command goes to:

• The Vue component when used on a component
• The variable wherever it is defined when used on a variable

What is actually happening?

When using "Go to Definition" or "Go to Type Definition" within the template, the result says "no definition found". When looking at the Extension Host logs, this message appears:

2026-05-20 14:21:43.257 [error] Error: <semantic> TypeScript Server Error (6.0.3)
Cannot read properties of undefined (reading 'getSourceFile')
TypeError: Cannot read properties of undefined (reading 'getSourceFile')
    at getValidSourceFile (c:\Program Files\Microsoft VS Code\0958016b2a\resources\app\extensions\node_modules\typescript\lib\typescript.js:153417:32)
    at Object.getDefinitionAtPosition2 [as getDefinitionAtPosition] (c:\Program Files\Microsoft VS Code\0958016b2a\resources\app\extensions\node_modules\typescript\lib\typescript.js:153955:71)
    at IpcIOSession.findSourceDefinition (c:\Program Files\Microsoft VS Code\0958016b2a\resources\app\extensions\node_modules\typescript\lib\typescript.js:196043:38)
    at findSourceDefinition (c:\Program Files\Microsoft VS Code\0958016b2a\resources\app\extensions\node_modules\typescript\lib\typescript.js:194941:43)
    at c:\Program Files\Microsoft VS Code\0958016b2a\resources\app\extensions\node_modules\typescript\lib\typescript.js:197591:15
    at IpcIOSession.executeWithRequestId (c:\Program Files\Microsoft VS Code\0958016b2a\resources\app\extensions\node_modules\typescript\lib\typescript.js:197580:14)
    at IpcIOSession.executeCommand (c:\Program Files\Microsoft VS Code\0958016b2a\resources\app\extensions\node_modules\typescript\lib\typescript.js:197589:29)
    at IpcIOSession.onMessage (c:\Program Files\Microsoft VS Code\0958016b2a\resources\app\extensions\node_modules\typescript\lib\typescript.js:197637:68)
    at process.<anonymous> (c:\Program Files\Microsoft VS Code\0958016b2a\resources\app\extensions\node_modules\typescript\lib\_tsserver.js:519:14)
    at process.emit (node:events:519:28)
    at emit (node:internal/child_process:949:14)
    at process.processTicksAndRejections (node:internal/process/task_queues:90:21)
	at r.create (c:\Program Files\Microsoft VS Code\0958016b2a\resources\app\extensions\typescript-language-features\dist\extension.js:24:168)
	at r.dispatchResponse (c:\Program Files\Microsoft VS Code\0958016b2a\resources\app\extensions\typescript-language-features\dist\extension.js:26:2654)
	at r.dispatchMessage (c:\Program Files\Microsoft VS Code\0958016b2a\resources\app\extensions\typescript-language-features\dist\extension.js:26:1162)
	at ChildProcess.<anonymous> (c:\Program Files\Microsoft VS Code\0958016b2a\resources\app\extensions\typescript-language-features\dist\extension.js:26:379)
	at ChildProcess.emit (node:events:519:28)
	at emit (node:internal/child_process:949:14)
	at process.processTicksAndRejections (node:internal/process/task_queues:90:21)

Another message that might appear in Extension Host is this:

[error] Error: <semantic> TypeScript Server Error (6.0.3)
Debug Failure. False expression: Script kind should match provided ScriptKind:3 and sourceFile.scriptKind: 1, !entry: false
Error: Debug Failure. False expression: Script kind should match provided ScriptKind:3 and sourceFile.scriptKind: 1, !entry: false
    at getDocumentRegistryEntry **********************\node_modules\typescript\lib\typescript.js:144625:11)
    at acquireOrUpdateDocument **********************\node_modules\typescript\lib\typescript.js:144655:32)
    at Object.acquireDocumentWithKey **********************\node_modules\typescript\lib\typescript.js:144591:12)
    at getOrCreateSourceFileByPath **********************\node_modules\typescript\lib\typescript.js:153603:31)
    at Object.getOrCreateSourceFile **********************\node_modules\typescript\lib\typescript.js:153582:14)
    at d:\Projects-Ethode\te-dotcms\node_modules\typescript\lib\typescript.js:153503:42
    at Object.getSourceFileWithCache [as getSourceFile] **********************\node_modules\typescript\lib\typescript.js:126901:24)
    at findSourceFileWorker **********************\node_modules\typescript\lib\typescript.js:129221:23)
    at findSourceFile **********************\node_modules\typescript\lib\typescript.js:129138:20)
    at d:\Projects-Ethode\te-dotcms\node_modules\typescript\lib\typescript.js:129089:22
    at getSourceFileFromReferenceWorker **********************\node_modules\typescript\lib\typescript.js:129060:26)
    at processSourceFile **********************\node_modules\typescript\lib\typescript.js:129087:5)
    at processRootFile **********************\node_modules\typescript\lib\typescript.js:128919:5)
    at d:\Projects-Ethode\te-dotcms\node_modules\typescript\lib\typescript.js:127692:41
    at forEach **********************\node_modules\typescript\lib\typescript.js:2309:22)
    at createProgram **********************\node_modules\typescript\lib\typescript.js:127692:5)
    at synchronizeHostDataWorker **********************\node_modules\typescript\lib\typescript.js:153534:15)
    at synchronizeHostData **********************\node_modules\typescript\lib\typescript.js:153429:7)
    at Object.getProgram **********************\node_modules\typescript\lib\typescript.js:153611:5)
    at AuxiliaryProject.updateGraphWorker **********************\node_modules\typescript\lib\typescript.js:188869:41)
    at AuxiliaryProject.updateGraph **********************\node_modules\typescript\lib\typescript.js:188692:32)
    at updateProjectIfDirty **********************\node_modules\typescript\lib\typescript.js:190535:36)
    at AuxiliaryProject.getLanguageService **********************\node_modules\typescript\lib\typescript.js:188289:7)
    at IpcIOSession.findSourceDefinition **********************\node_modules\typescript\lib\typescript.js:196042:31)
    at findSourceDefinition **********************\node_modules\typescript\lib\typescript.js:194941:43)
    at d:\Projects-Ethode\te-dotcms\node_modules\typescript\lib\typescript.js:197591:15
    at IpcIOSession.executeWithRequestId **********************\node_modules\typescript\lib\typescript.js:197580:14)
    at IpcIOSession.executeCommand **********************\node_modules\typescript\lib\typescript.js:197589:29)
    at IpcIOSession.onMessage **********************\node_modules\typescript\lib\typescript.js:197637:68)
    at process.<anonymous> **********************\node_modules\typescript\lib\_tsserver.js:519:14)
    at process.emit (node:events:519:28)
    at emit (node:internal/child_process:949:14)
    at process.processTicksAndRejections (node:internal/process/task_queues:90:21)
	at r.create (c:\Program Files\Microsoft VS Code\0958016b2a\resources\app\extensions\typescript-language-features\dist\extension.js:24:168)
	at r.dispatchResponse (c:\Program Files\Microsoft VS Code\0958016b2a\resources\app\extensions\typescript-language-features\dist\extension.js:26:2654)
	at r.dispatchMessage (c:\Program Files\Microsoft VS Code\0958016b2a\resources\app\extensions\typescript-language-features\dist\extension.js:26:1162)
	at ChildProcess.<anonymous> (c:\Program Files\Microsoft VS Code\0958016b2a\resources\app\extensions\typescript-language-features\dist\extension.js:26:379)
	at ChildProcess.emit (node:events:519:28)
	at emit (node:internal/child_process:949:14)
	at process.processTicksAndRejections (node:internal/process/task_queues:90:21)

Oddly enough, hovering over the components and variables to get information about them seems to be fine.

Alt+clicking on prop names takes you to the component as expected, but no idea why "go to definition" is failing on most other things within <template>. "Go to definition" also seems to work fine within the <script> portion of the component.

Link to minimal reproduction

https://github.com/x0rsw1tch/vuejs-lsp-bug-test

Any additional comments?

I don't know if this is an issue with Vue (Official), or with Typescript Language Features.

[KazariEX]

v3.2.9 from the marketplace and this one which one works?

[x0rsw1tch]

v3.2.9 from the marketplace and this one which one works?

Same issue with 3.2.9, I tried a handful of older versions back to 3.1.2, but no luck.

[KazariEX]

Cannot reproduce it on my end, I believe finding the last working version would be very helpful.

[KazariEX]

Have you enabled js/ts.preferGoToSourceDefinition option?

[KazariEX]

After investigation, the issue appears to be caused by tsserver's source definition lookup flow. When handling findSourceDefinition, tsserver creates an additional AuxiliaryProject, but this project does not load or run tsserver plugins. As a result, .vue files are not processed by the Vue plugin, and TS falls back to ScriptKind.TS when calling ensureScriptKind.

However, the actual .vue file uses the default lang="js", so in the main project it is exposed by the Vue plugin as ScriptKind.JS. This means the same file is treated as different ScriptKinds across different projects, which violates TS DocumentRegistry's consistency invariant and eventually triggers the debug failure.

As a workaround, disable js/ts.preferGoToSourceDefinition option, or change the related SFC to use lang="ts".

[x0rsw1tch]

Have you enabled js/ts.preferGoToSourceDefinition option?

As a matter of fact I did, but I really only used that in a Svelte-specific project. Turning that off does fix the problem for me, thank you!