Refactor controllers 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.

Start by locating the controllers and config-related error-handling code in the repository, then review how current errors are produced. Clarify which cases need more detail and how existing debugging output is structured. Done means the relevant configuration errors are more descriptive without changing unrelated behavior; the issue does not name specific tests to run.

Written by the indexing model from the issue text.