Add TypeScript types for services

**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 core services and any existing TypeScript type definitions. Clarify whether the intended completion is adding service types, improving error handling, or both, then identify the relevant checks or tests that demonstrate the new types and more descriptive errors.

Written by the indexing model from the issue text.