Optimize api for large datasets

**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 and the existing error-message paths described in the issue. Compare the current messages with the debugging context, then define completion as detailed, consistent errors for the relevant route failures; the issue does not name files or tests to run.

Written by the indexing model from the issue text.