Refactor types for better readability

**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.

Start by inspecting the error-handling code under lib and identify where current errors are created or reported. Done means the relevant errors provide more descriptive messages and the existing behavior remains intact; the issue does not name specific files or tests to run.

Written by the indexing model from the issue text.