Improve error messages in validation

**Problem**
When working with helpers, 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 validation entry points are named. Start by locating the helper validation and existing error-handling paths, then determine which cases need more descriptive messages and add coverage showing the improved errors.

Written by the indexing model from the issue text.