Refactor middleware for better readability

**Problem**
When working with config, the error messages could be more descriptive.

**Suggestion**
Improve error handling and add detailed error messages.

**Context**
This would help with debugging and maintenance.

Locate the middleware and configuration error-handling paths in the repository and read how current errors are generated. Identify which messages lack useful detail, then define completion as clearer error messages and improved error handling, verified against the affected behavior.

Written by the indexing model from the issue text.