Allow server side redirect on 404 / 500 error.

[thebells1111]

Is your feature request related to a problem? Please describe.
I can't figure out how to redirect to the index page on a 404 error without using client side routing after onMount.

Describe the solution you'd like
A way for the server to detect a status code and redirect to the desired route .

Describe alternatives you've considered
Perhaps implementing some sort of preload this.redirect in the _error.svelte template that also has access to the status code so the redirect can be based on the status code.

How important is this feature to you?
I think for certain apps, i.e. a timesheet app for logging employee time, having all 404 routes lead to the index (which is the timesheet page) leads to a cleaner feeling app. On some apps, going to a 404 and having to click out of it can feel clunky or like something is broken (which in a way is), but redirecting to main page makes the app feel more polished.

[evdama]

this seems to be the PR for this issue #960

I think an automatic server side redirect on a 404 to, for example, the main index.svelte in my app, would make a lot of sense. I would imagine other people have similiar use cases.

What's the verdict on this PR? makes sense? should be merged?

[PatrickG]

I don't really know why anybody would want to do this. I think the user should know that he hit a 404.

But this should be possible in the _error.svelte file.

<script>
  import { goto } from '@sapper/app';

  export let error;
  export let status;

  if (status == 404) {
    goto('/');
  }
</script>

[evdama]

It's written above why... can feel clunky
This depends a lot on the site and the people providing as well as using it, for some it might be as you say, for others quite the opposite.

Using _error.svelte like this would do a redirect, which is what this PR whould also avoid because of the server side redirect.

[thebells1111]

The problem I have found with using _error.svelte to do the redirect is it results in two page loads. One to the error page, and the other to the redirect page. On certain apps I've written, it can be jarring to have the screen flash white for a second. With a server side redirect, the change from one page to another is cleaner.