Update lib documentation

**Problem**
When working with models, 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 library's model-related error handling and any existing tests for error messages. Review the current messages and documentation, then define completion as clearer model errors with corresponding documentation updates and passing tests.

Written by the indexing model from the issue text.