[Client] Don't crash when receiving certain packets from NULL players

apps/openmw/mwmp/processors/player/ProcessorPlayerFaction.hpp

@@ -20,8 +20,10 @@ namespace mwmp
             {
                 // Entire faction membership cannot currently be requested from players
             }
-            else
+            else if (player != 0)
+            {
                 static_cast<LocalPlayer*>(player)->setFactions();
+            }
         }
     };
 }

apps/openmw/mwmp/processors/player/ProcessorPlayerJournal.hpp

@@ -24,8 +24,10 @@ namespace mwmp
             {
                 // Entire journal cannot currently be requested from players
             }
-            else
+            else if (player != 0)
+            {
                 static_cast<LocalPlayer*>(player)->addJournalItems();
+            }
         }
     };
 }

apps/openmw/mwmp/processors/player/ProcessorPlayerTopic.hpp

@@ -20,8 +20,10 @@ namespace mwmp
             {
                 // Entire list of topics cannot currently be requested from players
             }
-            else
+            else if (player != 0)
+            {
                 static_cast<LocalPlayer*>(player)->addTopics();
+            }
         }
     };
 }