Improve error messages in types

**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 model-related type handling and its current error paths; the issue names no files or tests. Trace where these errors are produced and document the existing cases before deciding how descriptive messages should be verified. Done means the relevant model errors provide clearer debugging context, with coverage for the changed cases if the project has tests.

Written by the indexing model from the issue text.