Improve error messages in data

**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 points generally to lib; start by inspecting the error-handling paths there and cataloging the current messages. Done means the affected errors provide more descriptive debugging context without changing unrelated behavior.

Written by the indexing model from the issue text.