Improve services performance

**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.

The issue names only the core services and does not identify files or tests. Start by locating the core service error-handling entry points and reviewing the current messages. Done means the requested error cases have more descriptive messages and the relevant checks pass.

Written by the indexing model from the issue text.