Improve auth performance

**Problem**
When working with handlers, 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 locating the handler code and its current error-handling paths. Clarify whether the requested change concerns authentication performance, as the title suggests, or descriptive error messages, as the body suggests; done should mean an agreed scope and verifiable behavior for the selected error cases.

Written by the indexing model from the issue text.