MQTT topic routing doesn't correctly reject pub/sub requests

[vordimous]

Describe the bug
Single topic MQTT setup with no default exit:

    routes:
      - when:
          - publish or subscribe:
              - topic: place/#

• When a singular route is defined for just publish or subscribe with no default exit, Zilla is still allowing both pub/sub with correct message delivery.
• Zilla is correctly rejecting publish requests when the topic pattern doesn't match but is still allowing all subscribe requests to succeed without an error.

To Reproduce
Create a single topic MQTT route with no default exit and publish a message to the correct topic while being subscribed. The pub/sub behavior does not adhere to the zilla.yaml.

Expected behavior
when only one pub or sub is defined the appropriate error code should be given for the other.