Add unit tests for components

**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 the existing unit-test setup for components. Review how handler errors are currently produced, then add coverage and more descriptive messages; the work is done when the relevant tests pass and failures provide useful debugging context.

Written by the indexing model from the issue text.