Consider deprecating old helpers API

**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 old helpers API and the model error-handling paths in the repository; no file or test is named in the issue. Clarify which helpers are being deprecated, the compatibility or migration behavior required, and the error-message cases that define done before changing anything.

Written by the indexing model from the issue text.