Refactor auth for better readability

**Problem**
When working with routes, the error messages could be more descriptive.

**Suggestion**
Improve error handling and add detailed error messages.

**Context**
This would help with debugging and maintenance.

Start by locating the route authentication and error-handling entry points, since the issue names no files or tests. Trace the current auth errors and identify where their messages are assembled; done means the auth flow is easier to read and route failures provide more descriptive debugging information.

Written by the indexing model from the issue text.