Improve error messages in middleware

**Feature request**
It would be great to have export for store.

**Use case**
Many users need this functionality for production deployments.

**Implementation idea**
Add a new config option `enable_export` with default `false`.

Start by locating the middleware implementation and the configuration entry points in the repository. Confirm how store export is expected to work and where configuration defaults are defined. Done should include the new enable_export option defaulting to false and a clear error or behavior for the requested export path.

Written by the indexing model from the issue text.