Improve types performance

**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, so first locate the model-related error handling and review existing error-message tests. Done means the affected errors provide more descriptive messages and the relevant tests cover the improved behavior.

Written by the indexing model from the issue text.