Fix race condition in language client visibility notifications

[Copilot]

The SourceMap › should jump to QL code test was failing intermittently on Windows with "Client is not running" errors. The notifyVisibilityChange() method was sending notifications before the language client finished starting.

Changes

Added an isRunning() guard in CodeQLLanguageClient.notifyVisibilityChange():

notifyVisibilityChange(editors: readonly TextEditor[]) {
  if (!this.isRunning()) {
    return;
  }
  // ... send notification
}

This matches the pattern used elsewhere in the codebase (e.g., extension.ts:201).

Original prompt

Fix the failing GitHub Actions workflow CLI Test (windows-latest, nightly)

Analyze the workflow logs, identify the root cause of the failure, and implement a fix.

Job ID: 59862639705

Job URL: https://github.com/github/vscode-codeql/actions/runs/20836665105/job/59862639705

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[cklin]

This is not the right solution.

[Copilot]

Pull request overview

This PR fixes an intermittent race condition in the CodeQL language client where visibility notifications were being sent before the language client finished starting, causing "Client is not running" errors in Windows tests.

Changes:

• Added an isRunning() guard in CodeQLLanguageClient.notifyVisibilityChange() to prevent sending notifications before the client is fully started

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[cklin]

I thought about it more and explored a different approach through #4274.

Ideally, we should get to the bottom of the underlying race condition. But the editor visibility change is not really under our control, and there is not much point for the extension to notify itself of the visibility change if it (the extension) had already stopped running. So I think this is the best way to mitigate the flaky test.