Improve server error logging

[hamboomger]

Partly resolves #13862.

This PR sanitizes stack trace for server errors by finding the last occurrence of "+page.", "+server.", or "+layout." in the stack trace, and removing everything that comes after that line.

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• Ideally, include a test that fails without this PR but passes with it.

Tests

As for the tests, I couldn't find a way to write Playwrite tests for the server logs. I dug up some similar tests, but they only test the error object itself, not the server log messages.

It seems like you can't easily listen on the server logs in Playwright, so if we really need it, I'd have to intercept the console.log(...) statements with something like this:

  const originalError = console.error;
  console.error = (...args) => {
    globalThis.__collected_errors = globalThis.__collected_errors || [];
    globalThis.__collected_errors.push(args);
    originalError(...args);
  };

• Run the tests with pnpm test and lint the project with pnpm lint and pnpm check

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Edits

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Latest commit: 8ba9932

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[hamboomger]

Please tell me if I should delete the changes from the playground directory 🙂

[svelte-docs-bot]

Preview: https://svelte-dev-git-preview-kit-13990-svelte.vercel.app/

[hamboomger]

Just the result of pnpm format on packages/kit, I didn't actually make any changes there.

[benmccann]

Can you please update the PR title to more specifically describe how error logging is being improved?