Allow redirects from handleError server hook

Describe the problem

Currently, I'm throwing an "unexpected" error so that I can get access to the event object to add information, returning an error object with a flag, and then redirecting when it gets back to the layout if it contains the flag. The error is an auth error in a generic request wrapper so it gets used in lots of places that would make passing in event or page information difficult.

Describe the proposed solution

Allow for redirecting from the handleError server hook so that there doesn't need to be an extra return trip.

Alternatives considered

Adding a hook for expected errors. This way I could throw the redirect whenever but still have access to a hook point where I could transform the redirect (e.g. adding in return info).

Importance

would make my life easier

Additional Information

No response

Start by tracing the server-side handleError hook and the existing redirect handling path. Determine how a redirect could be initiated from that hook without the extra return trip, and verify that the completed behavior supports the authentication-error scenario described in the issue.