Add unit tests for controllers

**Problem**
When working with middleware, 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 controllers and middleware referenced by the issue and inspect their current error paths. No files or test entry points are named, so clarify the expected error messages and affected cases before implementing. Done means controller unit tests cover the middleware errors and the messages are more descriptive.

Written by the indexing model from the issue text.