Update api documentation

**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 reading the lib directory and the API documentation to identify which error messages and documentation entries are in scope. Confirm the expected level of detail with maintainers, then verify that the updated documentation reflects the agreed error-handling changes.

Written by the indexing model from the issue text.