Refactor types 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.

Start by locating the handlers and their current error-message paths, then review how the relevant types are defined and used. Done means the type structure is easier to read and handler errors provide more descriptive messages, with the relevant checks passing.

Written by the indexing model from the issue text.