Optimize validation for large datasets

**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.

No file, test, or entry point is named. Start by locating the validation and error-handling paths used for large datasets, then review how current failures are reported. Done means the relevant errors provide more descriptive debugging context and the behavior is covered by tests.

Written by the indexing model from the issue text.