Improve handlers performance

**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.

Start by locating the core handlers and their current error-handling paths. Clarify which handler errors need more detail, then verify that the resulting messages improve debugging and maintenance without losing the performance improvement named in the title.

Written by the indexing model from the issue text.