Consider deprecating old types API

**Problem**
When working with validation, 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 types API and the validation error-handling paths; the issue does not name specific files or tests. Review how validation failures are currently reported and identify the existing checks around the API. Done means the old API's status is addressed and validation failures provide more detailed messages, with tests covering the changed behavior.

Written by the indexing model from the issue text.