Merge JoinMarket-Org/joinmarket-clientserver#1413: Account for missing nick fields in OnionPeer

bfb0e25861 Account for missing nick fields in OnionPeer (Adam Gibson)

Pull request description:

  Prior to this commit, if a message (like a disconnection control message), was to be sent to live peers, regarding another peer that did not have a nick field set, a crash would occur in directory nodes sending this message, because the function
  OnionPeer.get_nick_peerlocation_ser() assumed the existence of the nick field, and raised the OnionPeerError exception if it did not exist.

  After this commit, the raising of this Exception is caught when calling OnionPeer.get_nick_peerlocation_ser, so that a peer in this state is just not added to the list of peers to be sent to live peers. This condition is caused specifically by the fact that said peer has not completed a handshake (which must always pass the value of the nick), and so the other live peers will not yet be aware of it.

ACKs for top commit:
  kristapsk:
    cr utACK bfb0e25861

Tree-SHA512: 7bf1fe216bc7088b986a9f33c65fa07e25a5ec09a42cafc7496567b628a1e3b03e91b6554b9d66f6e0603d8ee15a729f6af76fed4a75ecbdf385a78d8cd4100b

jmdaemon/jmdaemon/onionmc.py

@@ -1505,7 +1505,11 @@ class OnionMessageChannel(MessageChannel):
             # since the peer may already be removed from self.peers,
             # we don't limit except by filter:
             for p in peer_filter:
-                peerlist.add(p.get_nick_peerlocation_ser() + NICK_PEERLOCATOR_SEPARATOR + "D")
+                try:
+                    peerlist.add(p.get_nick_peerlocation_ser(
+                        ) + NICK_PEERLOCATOR_SEPARATOR + "D")
+                except OnionPeerError:
+                    pass
         # For testing: dns won't usually participate:
         peerlist.add(self.self_as_peer.get_nick_peerlocation_ser())
         # don't send an empty set (will not be possible unless