Display error modal on API failures #1
Description
Currently, if the frontend loads but the backend server is down (most likely due to a server update, respinning containers), all API requests fail silently. Users will see that they are apart of no groups or groups have no projects, which can be very confusing and misleading.
We should implement a global error handler in the frontend. If an API request fails with a network error (like net::ERR_CONNECTION_REFUSED), it should stop any loading spinners and immediately show a full-screen, blocking modal.