Properly handle unauthenticated users

[JVT038]

Description

When a user currently visits a page (such as the settings page) while not being logged in, they simply get a blank screen. In the logs (and the network panel), it can be seen that there is a 403 HTTP response, but the user doesn't see this on the page itself.

Desired Behavior

The user should be redirected to the login page and maybe an error / warning that the user is trying to visit a page while they aren't logged in.

When the user logs in, the user should be redirected back to the page they were trying to access before.

Additional Context

No response