Add unit tests for types

**Problem**
When working with utils, 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 utils code that handles types and the repository's existing unit-test setup. Review current error handling and tests, then define coverage for type-related failures and verify that errors provide more descriptive messages.

Written by the indexing model from the issue text.