Add TypeScript types for lib

**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.

Start by locating the library referenced in the title and inspect how its public API is defined. The issue does not name files, tests, or specific types, and its body instead discusses generic error messages. Done is not defined; clarification is needed on the library surface and the expected TypeScript types or error-handling changes.

Written by the indexing model from the issue text.