Dispatch error should be preventable

[Ocramius]

Please see the tests.

It is currently impossible for a listener of Zend\Mvc\MvcEvent::EVENT_DISPATCH_ERROR to do following:

$event->setError(''); // resetting app state (not an error)
$event->setRouteMatch(...); // setting a route match (allows for redirecting to a controller in case of routing failure)
$event->stopPropagation();

This PR fixes that

[Ocramius]

@weierophinney assigning you since you probably know why that early return $this; was in place.

[weierophinney]

I'd argue that if we're not going to return out of the parent conditional, this conditional can be removed, as it's repeated immediately below.

[weierophinney]

@weierophinney assigning you since you probably know why that early return $this; was in place.

Honestly, I cannot quite remember. On review today, I don't see any good reason why, and clearly that use case is not covered by the tests, as your change doesn't lead to new failures.