Add rate limiting for import

**Problem**
When working with core, 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 import entry point and the core error-handling paths referenced by the issue. Clarify whether the intended change is rate limiting, more descriptive errors, or both; done should include a documented behavior and tests covering the chosen import and error cases.

Written by the indexing model from the issue text.