Improve parsers performance

**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, entry points, or tests. Start by locating the parser and model error-handling code, then determine the current failure cases and how detailed messages should be specified; done means the relevant errors provide more descriptive debugging information and the existing checks still pass.

Written by the indexing model from the issue text.