Added sanity-check.

git-svn-id: http://svn.igniterealtime.org/svn/repos/messenger/branches/jive_messenger_2_1_branch@1443 b35dd754-fafc-0310-a699-88a17e54d16e

src/java/org/jivesoftware/messenger/muc/spi/MUCRoleImpl.java

@@ -203,6 +203,9 @@ public class MUCRoleImpl implements MUCRole {
     }
 
     public void send(Packet packet) {
+        if (packet == null) {
+            return;
+        }
         packet.setTo(user.getAddress());
         router.route(packet);
     }