Worker shadows `onUserConsoleLog` with `undefined`, crashing vitest's `logFailedTask` when `silent: 'passed-only'`

[rhwinter]

Describe the bug

dist/workerNew.js (and workerLegacy.js) mutates every non-own reporter with:

p.reporters.forEach(e => { e instanceof Z || (e.onUserConsoleLog = void 0) });

That assigns undefined as an instance property, shadowing BaseReporter.prototype.onUserConsoleLog. When test.silent: 'passed-only' is set and a failing test has captured console output, vitest's inherited BaseReporter.logFailedTask calls this.onUserConsoleLog(log, "failed") unguarded and throws TypeError: this.onUserConsoleLog is not a function. The dispatcher catches it and prints Unhandled Reporter Error for every failed test/suite/module — and the failing test's captured logs (which passed-only exists to surface) are silently dropped.

Suggested fix: don't delete the inherited method. Either assign a no-op (e.onUserConsoleLog = () => {}) or override e.shouldLog = () => false to suppress the duplicate terminal output while keeping the prototype contract intact.

Verified: same vitest config run from the CLI (no extension) does not crash — onUserConsoleLog is resolvable. The crash only appears when the extension's mutation has run.

Environment: vitest.explorer@1.50.4, vitest@4.1.6 (also reproduced on 4.0.18; same pattern present on vitest main).

Expected behavior

When silent: 'passed-only' is set and a failing test has captured console output, that captured output should be replayed under the failure banner — same as it is when running vitest directly from the CLI. Instead, the reporter dispatch crashes with Unhandled Reporter Error and the logs are silently dropped.

Reproduction

Minimal repro repo with deterministic forced repro + analysis: https://github.com/rhwinter/vitest-loggingError

git clone https://github.com/rhwinter/vitest-loggingError
cd vitest-loggingError
npm install
npm run repro:forced

broken-reporter.js mirrors the extension's exact mutation (reporter.onUserConsoleLog = undefined on a DefaultReporter instance). Stack trace produced is frame-for-frame identical (modulo reporter class name) to the one we see from the extension:

TypeError: this.onUserConsoleLog is not a function
 ❯ ExtensionShadowedReporter.logFailedTask  …/index.UpGiHP7g.js:2239:78
 ❯ ExtensionShadowedReporter.onTestCaseResult …/index.UpGiHP7g.js:2229:50
 ❯ ExtensionShadowedReporter.onTestCaseResult …/index.UpGiHP7g.js:3123:9
 ❯ Vitest.report / TestRun.reportEvent / TestRun.updated / Proxy.onTaskUpdate

Output

The only visible side-effect here is the premature WebSocket close at the end of the run.


[10:19:03 PM] [API] Filtering projects: repro
[INFO 10:19:03 PM] [API] Running Vitest v4.1.6 (vitest-loggingError/vitest.config.js) with "/Users/.../.local/state/fnm_multishells/69887_1779131127156/bin/node /Users/.../.vscode/extensions/vitest.explorer-1.50.4/dist/worker.js"
[10:19:03 PM] Enqueuing "failing test with console output → reporter crashes"
[INFO 10:19:03 PM] Running 1 file(s) with name pattern: ^\s?failing test with console output → reporter crashes$
[INFO 10:19:04 PM] [DECOR] Reset all decorations.
[10:19:04 PM] No task result for "repro.test.js [repro]", ignoring
[10:19:04 PM] Enqueuing "failing test with console output → reporter crashes"
[10:19:04 PM] No errors found for "repro.test.js [repro]"
[10:19:04 PM] Marking "failing test with console output → reporter crashes" as failed with 1 errors
[10:19:04 PM] No errors found for "repro.test.js [repro]"
[10:19:04 PM] Ending test run repro.test.js
[10:19:04 PM] Disposing test runner
[10:19:04 PM] [API] Vitest WebSocket connection closed, cannot call RPC anymore.

Extension Version

vitest.explorer@1.50.4

Vitest Version

vitest@4.1.6 (also reproduced on 4.0.18; same code path on main/5.0.0-beta.2)

Validations

• Check that you are using the latest version of the extension
• Check that there isn't already an issue that reports the same bug to avoid creating a duplicate.
• Check that this is a concrete bug. For Q&A open a GitHub Discussion or join our Discord Chat Server.
• The provided reproduction is a minimal reproducible example of the bug.