Increase test coverage

Currently we're running into issues because we are not really testing much and end up making breaking changes without noticing. I think we should be working on improving this. I propose unit tests to be build for the following:

- [ ] Both types of authentication.
- [ ] Changing the settings.
- [ ] All functions which have routes.
- [x] Tests for all endpoints to check if authentication is asked like expected.

I think this would be most of what would be needed.

Start by locating the authentication paths, settings-changing code, and functions with routes mentioned in the issue, then review the existing endpoint authentication tests. Done means unit tests cover both authentication types, settings changes, and all routed functions, while preserving the already-covered endpoint authentication checks.

Written by the indexing model from the issue text.