Optimize core for large datasets

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

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

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

No files, entry points, or tests are named, and the title conflicts with the body. Start by locating service error handling and its existing tests, then clarify which errors need more detail and how the expected messages will be verified.

Written by the indexing model from the issue text.