Handle edge cases in export

**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 tests are named. Start by locating the route export entry point and tracing its current error paths; done means the identified edge cases produce descriptive error messages and the relevant checks pass.

Written by the indexing model from the issue text.