feat: support throwing error in handle

[ivanhofer]

Closes #7966 Heavily inspired by #7612; no new tests for the same reason described there.

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[ivanhofer]

My git cli says I don't have any changes to pull. Not sure how to bring this branch up2date.

[gtm-nayan]

did you pull from the master branch or your error-handle branch?

[ivanhofer]

did you pull from the master branch or your error-handle branch?

I pulled from master, and I also updated my fork to contain the latest changes from the original repo. Pulling directly from the original does not work either. Not sure what is broken.

[dummdidumm]

Tried a quick stab at this, it's trickier than I thought. Ideally we fall back to the static error page, but I'm not sure how to do that from a data response yet.

[ivanhofer]

Tried a quick stab at this, it's trickier than I thought. Ideally we fall back to the static error page, but I'm not sure how to do that from a data response yet.

Is the problem that it is a client-side navigation, the data request responds with json and can't be used to deliver the error page because it would be html? And we can't render the +error.svelte page because the hooks.server.js has no information about the rendering process because it never calls resolve(event)?

[dummdidumm]

We can't render +error.svelte because that included +layout.svelte, which might include a +layout.server.js, which means there's another handle call, which would yield the same error. Furthermore it would be inconsistent to show +error.svelte in the JS case an error.html in the SSR case.

[lukaszpolowczyk]

@ivanhofer @dummdidumm Is this somehow related? https://github.com/sveltejs/kit/issues/7914#issuecomment-1347002959

[gtm-nayan]

I was confused by the changes here, turns out the server is returning the correct response, Simon's right on handle_fatal_error being able to deal with this already, the problem is on the client side.

Here load_data creates an error object, which is caught and passed in here but there is no status information in that catch clause so it just shows a generic 500.

Also related and probably can be solved at the same time, because of the same "just thrown a native Error" mechanic, the HttpError from the server is never actually instantiated into an HttpError in the browser.

[ivanhofer]

@gtm-nayan thanks for your investigation. Haven't had the time to follow up on this issue. But it seems my assumption was wrong and this PR does not make sense at all. I will close it.