Improve config performance

**Problem**
When working with core, 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 entry points are named. Start by locating the core configuration and error-handling paths, then identify which messages are currently insufficient; done should mean a defined set of more descriptive errors with tests or other verification for the changed behavior.

Written by the indexing model from the issue text.