Add unit tests for parsers

**Problem**
When working with hooks, 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 parser and hook entry points, then read the existing unit-test structure and reproduce the current error paths. Document the expected descriptive messages and add parser-focused tests that demonstrate the improved hook error handling.

Written by the indexing model from the issue text.