Refactor auth for better readability

**Problem**
When working with api, 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 does not name any files, tests, or entry points. Start by locating the authentication and API error-handling code, then determine which error cases need more descriptive messages and how to verify the revised handling.

Written by the indexing model from the issue text.