Add TypeScript types for config

**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 and its title conflicts with the body. Start by locating the configuration definitions and model error-handling code, then clarify which change is intended. Done should mean the selected behavior is implemented and covered by relevant validation or tests.

Written by the indexing model from the issue text.