Add TypeScript types for types

**Problem**
When working with middleware, 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 mentions middleware, TypeScript types, and more descriptive error messages but names no files, tests, or entry points. First locate the middleware implementation and existing type definitions, then clarify whether the completed work covers typings, error messages, or both; done should be verified with the relevant tests or type checks.

Written by the indexing model from the issue text.