Improve api 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.

No files or tests are named. Start by locating the model-related error handling and API entry points, then identify which errors currently lack useful detail. Done means the relevant errors provide more descriptive messages and the behavior is covered by tests.

Written by the indexing model from the issue text.