Add unit tests for utils

**Problem**
When working with config, 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, configuration handling, and any existing unit-test entry points. Read how configuration errors are currently reported and run the relevant test suite. Done means unit tests cover the error paths and the resulting messages provide the requested debugging detail.

Written by the indexing model from the issue text.