UI gets stuck on "Fetching..." screen if a previously-selected school is unavailable

[MoralCode]

Describe the bug
If a school and/or bell schedule gets deleted from the database, all users who had that schedule selected previously will be shown a screen that says "Fetching" with no apparent way out.

This can be worked around by manually navigating to the /select page and selecting a new school from that list.

To Reproduce
Steps to reproduce the behavior:

1. Create a school (and optionally also a schedule) in the database
2. open the ClassClock app in a fresh browser tab/window with browsing data cleared for the classclock site
3. manually delete the schedule (and optionally also the school) from the database and create a new one with a different id.

Expected behavior
The page should detect the 404 error for the school and/or the schedule and either show the user an error or send them back to the select school page automatically.

[AlexVCS]

Hi, I'd like to work on this issue. Can you please assign it to me?

[MoralCode]

Done! Thanks for reaching out!

Let me know if you have any questions on how to reproduce this. I'm also pretty responsive on the slack/gitter channels for classclock if you would prefer a more chat-based style of communication.

The documentation on this project and the associated API (https://github.com/MoralCode/ClassClockAPI) is not quite where I would like it to be. I would love to know if there's any areas that are hard to understand for people who are new to the codebase.

I should probably also clarify that this issue is only present on the development branch.

[MoralCode]

@AlexVCS any updates on this? are you still interested in working on it?

[MoralCode]

Removed assignee due to lack of activity on this issue.

Dev branch has also been merged to main so this is now a mainline issue, but that said, it seems to only surface when a school is deleted, which is likely quite a rare event in most real-world production deployments