Custom error evaluation

The api I'm working with always returns an HTTP 200 whether an error has occurred or not. There is a `status` key that will either be "success" or "error" so what I'm looking for is a way to define how this middleware determines which action to dispatch when it receives a response based on something within the response object.

I was wondering if this is possible in the current implementation and if not how open you'd be to receive a PR for this functionality if it seems useful to others.