fix: allow HandleServerError hook to access the getRequestEvent

[geodask]

Resolves #13654: Allow HandleServerError hook to access getRequestEvent.

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Latest commit: bf4b94c

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@sveltejs/kit	Patch

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[svelte-docs-bot]

Preview: https://svelte-dev-git-preview-kit-13666-svelte.vercel.app/

[teemingc]

Have we also checked if getRequestEvent works in the server handleFetch hook too? and can we add a test?

[geodask]

I have verified that getRequestEvent works within handleFetch. I have added a test for handleError. Let me know if this approach is ok, or if I need to change or add anything.

[teemingc]

Thank you!