Fix crash

src/org/thoughtcrime/securesms/ApplicationContext.java

@@ -615,9 +615,11 @@ public class ApplicationContext extends MultiDexApplication implements Dependenc
         }
         Set<String> servers = DatabaseFactory.getLokiThreadDatabase(this).getAllPublicChatServers();
         for (String server : servers) {
+          if (profileKey != null) {
             publicChatAPI.setProfilePicture(server, profileKey, url);
           }
         }
+      }
     });
   }
   // endregion