Enrich listener leak error telemetry with kind and listenerCount

[bryanchen-d]

Summary

Adds kind and listenerCount fields to ListenerLeakError / ListenerRefusalError so that the error telemetry pipeline can report why a leak was detected and how many listeners were active.

Changes

src/vs/base/common/event.ts

• ListenerLeakError: add
  eadonly kind and
  eadonly listenerCount fields, plus a static is() with instanceof + structural fallback for cross-realm safety
• ListenerRefusalError: now extends ListenerLeakError (inherits fields, just overrides
  ame)
• Both constructors now accept listenerCount and pass it through to the call sites in LeakageMonitor.check() and Emitter.event

src/vs/platform/telemetry/common/errorTelemetry.ts

• Import ListenerLeakError from �vent.ts
• In _onErrorEvent(): check ListenerLeakError.is(err) and copy kind / listenerCount onto the buffered ErrorEvent
• GDPR classification types (ListenerLeakDiagEvent, ListenerLeakDiagFragment) defined at module level
• _flushBuffer() uses widened UnhandledErrorEvent / UnhandledErrorClassification types so the telemetry extractor discovers the new fields

Telemetry

The UnhandledError event gains two optional fields when the error is a listener leak:

Field	Classification	Value
kind	SystemMetaData / PerformanceAndHealth	'dominated' or 'popular'
listenerCount	SystemMetaData / PerformanceAndHealth	number of listeners at detection time

Non-leak errors are unaffected (fields absent).

[Copilot]

Pull request overview

Adds a new error subtype to attach diagnostic properties to errors and updates error telemetry to flatten those diagnostics into UnhandledError events, with initial adoption in listener leak/refusal errors.

Changes:

• Introduces ErrorWithDiagProps (diagProperties bag + is() guard) in src/vs/base/common/errors.ts.
• Updates ListenerLeakError/ListenerRefusalError to extend ErrorWithDiagProps and populate { kind, listenerCount }.
• Updates BaseErrorTelemetry to detect ErrorWithDiagProps and Object.assign diagnostics onto the telemetry payload.

Show a summary per file

File	Description
src/vs/base/common/errors.ts	Adds ErrorWithDiagProps for carrying diagnostic properties on errors.
src/vs/base/common/event.ts	Migrates listener leak/refusal errors to ErrorWithDiagProps and passes diagnostics.
src/vs/platform/telemetry/common/errorTelemetry.ts	Flattens diagnostic properties onto UnhandledError telemetry events.

Copilot's findings

Comments suppressed due to low confidence (1)

src/vs/platform/telemetry/common/errorTelemetry.ts:129

• New behavior (copying diagnostic properties into the UnhandledError payload) isn’t covered by tests. There are existing error telemetry tests under src/vs/platform/telemetry/test/browser/telemetryService.test.ts; please add a test that throws an ErrorWithDiagProps (or a subclass) and asserts the diagnostic fields are present in the logged event (and still go through PII cleaning).

		const errorEvent: ErrorEvent = { msg, callstack };

		// flatten diagnostic properties directly into the telemetry event
		if (ErrorWithDiagProps.is(err)) {
			Object.assign(errorEvent, err.diagProperties);
		}

		this._enqueue(errorEvent);

• Files reviewed: 3/3 changed files
• Comments generated: 2

[github-actions]

Screenshot Changes

Base: df0e1c53 Current: 2732d20a

Changed (14)

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[Copilot]

Pull request overview

Adds a generic mechanism for enriching unhandled error telemetry with structured diagnostic properties (with explicit GDPR classifications) so specific error types—starting with listener leak errors—can emit more useful triage data without hard-coupling the base telemetry pipeline to those error subclasses.

Changes:

• Introduces ErrorWithTelemetry to carry a diagProperties bag alongside an error.
• Extends listener leak/refusal errors to include { kind, listenerCount } diagnostics and makes BaseErrorTelemetry flatten these into the emitted event.
• Adds a DiagLogger registration mechanism and a listener-leak-specific registration module, activated via side-effect imports in platform-specific telemetry entrypoints.

Show a summary per file

File	Description
src/vs/base/common/errors.ts	Adds ErrorWithTelemetry and a type guard for identifying telemetry-enriched errors.
src/vs/base/common/event.ts	Updates listener leak/refusal errors to extend ErrorWithTelemetry and attach kind/listenerCount.
src/vs/platform/telemetry/common/errorTelemetry.ts	Exports ErrorEventFragment, adds DiagLogger registry + flattening/dispatch logic for enriched error telemetry.
src/vs/platform/telemetry/common/listenerLeakDiagTelemetry.ts	New GDPR-typed publicLogError2 call sites for leak/refusal diagnostics via registered loggers.
src/vs/platform/telemetry/browser/errorTelemetry.ts	Side-effect import to activate listener leak diagnostic logger registration in browser builds.
src/vs/platform/telemetry/node/errorTelemetry.ts	Side-effect import to activate listener leak diagnostic logger registration in node builds.
src/vs/platform/telemetry/electron-main/errorTelemetry.ts	Side-effect import to activate listener leak diagnostic logger registration in electron-main builds.

Copilot's findings

• Files reviewed: 7/7 changed files
• Comments generated: 3