Refactor models for better readability

**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.

The issue names no files, tests, or entry points. Start by locating the model code and its current error handling, then determine the exact message changes and how completion will be verified.

Written by the indexing model from the issue text.