Optimize lib for large datasets

**Problem**
When working with lib, 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 only identifies lib and does not name a file, failing case, or test. Start by locating the lib code and reproducing its current errors, then clarify whether the goal is large-dataset optimization or more descriptive error handling. Done means the intended error paths are improved with detailed messages and covered by relevant tests.

Written by the indexing model from the issue text.