Handle edge cases in import

**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 import handling and the existing error-message paths. Reproduce the reported edge cases, then define the missing details and verify that failures produce more descriptive messages; no specific files or tests are identified in the issue.

Written by the indexing model from the issue text.