Support import configuration

**Problem**
When working with validation, 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 provides no file, test, or entry point. Start by locating the validation and error-handling paths in the Shell-based CLI, then inspect existing error messages and tests. Done means the intended validation failures produce clearly defined, detailed messages and the relevant behavior is covered by tests.

Written by the indexing model from the issue text.