Allow CSR when server endpoints respond with a redirect

Describe the problem

I have server endpoints which always redirect to a page. To be clear, these endpoints redirect to different pages each time, so they can't just be skipped. It doesn't make sense to consider these endpoints as pages because they never display anything, but it does make sense to redirect to them. Currently, if I redirect to a server endpoint, it works fine, but it is done through page requests rather than CSR and the console shows Error: Not found: /server-endpoint.

Describe the proposed solution

SvelteKit should intercept, from the client, redirects made by server endpoints to allow for CSR

Alternatives considered

To avoid getting the error message, I could make the server endpoint respond with the new URL as part of the response body instead of the location header, then write my own redirection logic. However, there are a few problems with this:

• These endpoints won't exclusively be used via my app; I could send links to them elsewhere and I expect people who click the links to be redirected appropriately
• This wouldn't allow for CSR to work
• This involves writing my own logic, which would ideally be handled by SvelteKit

Importance

nice to have

Additional Information

No response

The issue names no files or tests. Start by tracing SvelteKit's client-side navigation handling for redirects returned by server endpoints, then verify that a redirect to varying destinations is intercepted during CSR without producing a not-found error.