Improve error messages in store

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

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

**Priority**: Low/Medium

Start by locating the store middleware and its existing error-message and export handling code. Check how current middleware exports behave, then define done as configurable export support with sensible defaults and clearer store errors, verified against the repository's existing checks.

Written by the indexing model from the issue text.