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API server panics in acquireConfigForFile when opening a JS file a tsconfig does not include #65054
Description
🔎 Search Terms
createSnapshot panic, acquireConfigForFile, configFileRegistryBuilder, SyncMapEntry ChangeIf nil pointer, typescript/sync openFiles .mjs .js inferred project
🕗 Version & Regression Information
- This changed between versions 7.0.2 and 7.1.0-beta
- It still reproduces on 7.1.0-dev.20261027.1 and 7.1.0-dev.20261029.1
⏯ Playground Link
No response
💻 Code
mkdir repro && cd repro
npm install typescript@7.1.0-beta
echo '{}' > tsconfig.json
echo 'export const a = 1' > w.mjs
node probe.mjs// probe.mjs
import { API } from 'typescript/sync'
const api = new API({ cwd: process.cwd() })
api.createSnapshot({ openFiles: [process.cwd() + '/w.mjs'] })
api.close()macOS arm64, Node 24.
🙁 Actual behavior
The API server crashes:
panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x2 addr=0x0]
github.com/microsoft/TypeScript/tsc/internal/project/dirty.(*SyncMapEntry[...]).ChangeIf(...)
tsc/internal/project/dirty/syncmap.go:128
github.com/microsoft/TypeScript/tsc/internal/project.(*configFileRegistryBuilder).acquireConfigForFile(...)
tsc/internal/project/configfileregistrybuilder.go:319
github.com/microsoft/TypeScript/tsc/internal/project.(*configFileRegistryBuilder).findOrAcquireConfigForFile(...)
tsc/internal/project/configfileregistrybuilder.go:135
github.com/microsoft/TypeScript/tsc/internal/project.(*ProjectCollectionBuilder).findOrCreateDefaultConfiguredProjectWorker.func2(...)
tsc/internal/project/projectcollectionbuilder.go:1108
github.com/microsoft/TypeScript/tsc/internal/core.BreadthFirstSearchParallelEx[...].func1-range1.1(...)
tsc/internal/core/bfs.go:115
🙂 Expected behavior
The JS file opens in the inferred project (/dev/null/inferred), as it does when there is no tsconfig, and as 7.0.2 (typescript/unstable/sync, updateSnapshot) did with this exact layout.
Additional information about the issue
- The same thing happens with
.js, and with the JS file one or two directories below the tsconfig. - With no tsconfig, the file opens in
/dev/null/inferredas expected. - If a
.tsfile the tsconfig includes sits in the same directory as the JS file, it also opens fine.
We hit this in a repository validator that opens every source file in a checkout, including stray .mjs and .cjs build scripts that no tsconfig includes.
Activity
Skip every file TypeScript 7.1.0-beta crashes on, not just solution-s…
ycmjason commentedon Oct 30, 2026
Same panic (
acquireConfigForFile→SyncMapEntry.ChangeIf) with.tsfiles too. It seems to trigger whenever the nearesttsconfig.jsonmatches no files of its own and doesn't include the opened file, regardless of extension:tsconfig.json{"files":[],"references":[{"path":"./a"}]}x.ts(alsoscripts/x.ts){"files":[]}x.ts{"include":["src"]},src/emptyx.ts{"include":["src"]},src/a.tsexistsx.ts{"files":["a.ts"],"references":[{"path":"./a"}]}x.tsThe first row is a common layout: a solution-style root tsconfig with a stray root file such as
vitest.config.ts.For comparison, the LSP server (
tsc --lsp --stdio) handlesdidOpenandhoverfor all of these layouts without crashing. Only the API'screateSnapshot({ openFiles })panics.Drop the TypeScript 7.1.0-beta crash workaround; wait for the upstrea…