Fix crash

--HG--
branch : trunk

src/game/Map.cpp

@@ -2524,7 +2524,7 @@ bool InstanceMap::CanEnter(Player *player)
     // cannot enter while an encounter is in progress on raids
     /*Group *pGroup = player->GetGroup();
     if(!player->isGameMaster() && pGroup && pGroup->InCombatToInstance(GetInstanceId()) && player->GetMapId() != GetId())*/
-    if (IsRaid() && GetInstanceData()->IsEncounterInProgress())
+    if (IsRaid() && GetInstanceData() && GetInstanceData()->IsEncounterInProgress())
     {
         player->SendTransferAborted(GetId(), TRANSFER_ABORT_ZONE_IN_COMBAT);
         return false;