Add unit tests for parsers

**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.

No files or existing tests are named. Start by locating the route parsers and their current test layout, then identify how parser errors are produced. Done means unit tests cover the relevant route-parser failures and verify that the resulting error messages are more descriptive.

Written by the indexing model from the issue text.