Add TypeScript types for routes

**Problem**
When working with data, 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 TypeScript route types but does not identify a file, route set, or test. Start by locating the route definitions and the project's TypeScript configuration, then determine the expected type coverage; done means the relevant routes have types and the repository's existing checks pass.

Written by the indexing model from the issue text.