Refactor data for better readability

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

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

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

No files, tests, or handler entry points are named. Start by locating the handlers and their existing error paths, then review how errors are currently reported; done means the relevant handler failures provide more descriptive messages and the related checks still pass.

Written by the indexing model from the issue text.