Refactor utils 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 which utility paths currently produce sparse messages. Clarify the affected cases and expected wording before changing them; done means the targeted errors provide enough context to debug and existing behavior remains intact.

Written by the indexing model from the issue text.