Improve handlers performance

**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 inspecting the handlers and error paths under lib. Determine which current messages lack useful detail, then verify that the affected errors provide clearer debugging information without changing unrelated behavior.

Written by the indexing model from the issue text.