Optimize middleware for large datasets

**Problem**
When working with handlers, 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 middleware and handler error-handling entry points, then review the existing messages and how failures are surfaced. Clarify which large-dataset paths are affected and define the expected descriptive wording; done means relevant handler failures provide enough context to aid debugging and maintenance.

Written by the indexing model from the issue text.