Optimize routes for large datasets

**Problem**
When working with core, the error messages could be more descriptive.

**Suggestion**
Improve error handling and add detailed error messages.

**Context**
This would help with debugging and maintenance.

The issue does not name files, tests, or a specific error path. Start by locating the core route-handling and error-handling entry points, then reproduce the large-dataset case and trace the current messages. Done means the relevant failures provide more descriptive errors and the existing checks still pass.

Written by the indexing model from the issue text.