Add TypeScript types for parsers

**Problem**
When working with data, 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 TypeScript types for parsers, but does not identify parser files, entry points, tests, or the expected error-message changes. First locate the parser implementation and its existing type or test coverage, then clarify which data and errors must be represented before defining completion.

Written by the indexing model from the issue text.