Improve error messages in middleware

**Description**
Currently middleware lacks proper export support.

**Proposed solution**
Add configurable export with sensible defaults.

**Priority**: Low/Medium

Start by locating the middleware implementation and reading how it currently handles exports and errors. Clarify whether the requested change is configurable export support or improved error messages, then define done as middleware exporting correctly with sensible defaults and useful failures.

Written by the indexing model from the issue text.