Add unit tests for routes

**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 handling code and the existing unit-test setup. Read how route errors are currently produced, then define tests for the expected descriptive messages and verify the error-handling behavior. Done means route-related failures have coverage and the messages provide the requested debugging context.

Written by the indexing model from the issue text.