Don't return an error on datasync Send

if an error is returned on the Send function, datasync will keep
  retrying a message at each epoch. If the message cannot be sent (for
  example is too large), then no messages will be sent until logout.

protocol/datasync/transport.go

@@ -59,7 +59,6 @@ func (t *NodeTransport) Watch() transport.Packet {
 }
 
 func (t *NodeTransport) Send(_ state.PeerID, peer state.PeerID, payload protobuf.Payload) error {
-	var lastError error
 	if t.dispatch == nil {
 		return errNotInitialized
 	}
@@ -74,21 +73,25 @@ func (t *NodeTransport) Send(_ state.PeerID, peer state.PeerID, payload protobuf
 
 		data, err := proto.Marshal(payload)
 		if err != nil {
-			return err
+			t.logger.Error("failed to marshal payload")
+			continue
 		}
 
 		publicKey, err := datasyncpeer.IDToPublicKey(peer)
 		if err != nil {
-			return err
+			t.logger.Error("failed to conver id to public key", zap.Error(err))
+			continue
 		}
+		// We don't return an error otherwise datasync will keep
+		// re-trying sending at each epoch
 		err = t.dispatch(context.Background(), publicKey, data, payload)
 		if err != nil {
-			lastError = err
 			t.logger.Error("failed to send message", zap.Error(err))
 			continue
 		}
 	}
-	return lastError
+
+	return nil
 }
 
 func splitPayloadInBatches(payload *protobuf.Payload, maxSizeBytes int) []*protobuf.Payload {