Better handling of unexpected requests/responses

Requests/responses leaking out of an Effect (and similarly
Producers/Consumers) can only be some kind of bottoms. Instead of
silently ignoring these we evaluate them, so the user is aware of the
error and gets the original error from the faulty
Effect/Producer/Consumer.
Merge pull request #88 from klao/fix_unexpecteds

Proposal for better handling of unexpected requests/responses