Remove peers from the node_id_to_descriptor even without init

When a peer has finished the noise handshake, but has not yet
completed the lightning `Init`-based handshake, they will be
present in the `node_id_to_descriptor` set, even though
`Peer::handshake_complete()` returns false. Thus, when we go to
disconnect such a peer, we must ensure that we remove it from the
descriptor set as well.

Failing to do so caused an `Inconsistent peers set state!` panic in
the C bindings network handler.

Author: TheBlueMatt

lightning/src/ln/peer_handler.rs

@@ -1951,11 +1951,10 @@ impl<Descriptor: SocketDescriptor, CM: Deref, RM: Deref, OM: Deref, L: Deref, CM
 			},
 			Some(peer_lock) => {
 				let peer = peer_lock.lock().unwrap();
-				if !peer.handshake_complete() { return; }
-				debug_assert!(peer.their_node_id.is_some());
 				if let Some((node_id, _)) = peer.their_node_id {
 					log_trace!(self.logger, "Handling disconnection of peer {}", log_pubkey!(node_id));
 					self.node_id_to_descriptor.lock().unwrap().remove(&node_id);
+					if !peer.handshake_complete() { return; }
 					self.message_handler.chan_handler.peer_disconnected(&node_id);
 					self.message_handler.onion_message_handler.peer_disconnected(&node_id);
 				}