401 Unauthorized response to check_session doesn't trigger logout

When a user's session has expired, the JWT token changes or a developer switches between a local backend and a cloud backend, reloading the dashboard triggers several API calls that return 401 (unauthorized) errors.

This triggers confusing errors in development:
In production, the dashboard appears stuck, with no indication of what's happened:
It should be up to `/auth/check_session` to check whether the session is still valid, and a 401 response to this should trigger a logout redirect, but this doesn't seem to be working properly.
Other API calls should ideally be paused until `check_session` has completed.