Optimize routes for large datasets

**Problem**
When working with lib, 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 relevant code under lib; the issue does not name a file, test, route, or failing command. Trace the current error-handling path and establish which messages need more detail, then add coverage showing that the resulting errors are more descriptive.

Written by the indexing model from the issue text.