Exception from is-identifiable service should not DLQ messages

[rkm]

Describe the bug

I encountered a scenario where the NERd socket service was not running and all incoming messages were sent to the DLQ.

Expected behavior

In this situation, the service should have exited with an exception and left the message on the queue instead.

To reproduce

Run the is-identifiable service with a socket classifier that is not available.

Additional context