fix: handling 404 when redirect from +layout.ts in SPA mode

[manhhungpc]

When redirect to an unknow route in SPA mode, which has a root load function in +layout.ts, it will fallback to the root +error.svelte instead of a blank page. See #11099. Issue #11494 seems to be releated

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[teemingc]

Thanks for opening this PR, although I’m not sure if this is the right solution. We need to load the root layout when rendering the root error page. I’m guessing the tests are failing because of the root layout node being omitted. I think we should be catching the error instead as I explained here https://github.com/sveltejs/kit/issues/11099#issuecomment-1823044646 adding a test for this scenario should help with testing the solution

[manhhungpc]

Thanks for pointing that out! And I'm working on your solution

[benmccann]

I've marked this as a draft for now. Please hit "ready for review" when it's ready for another look

[teemingc]

closed in favour of https://github.com/sveltejs/kit/pull/12005