Fix BG create, stop and start related crashes

Author: Foereaper

src/server/game/Battlegrounds/Battleground.cpp

@@ -139,8 +139,9 @@ Battleground::Battleground()
 Battleground::~Battleground()
 {
 #ifdef ELUNA
-    if (Eluna* e = GetBgMap()->GetEluna())
-        e->OnBGDestroy(this, GetTypeID(), GetInstanceID());
+    if(m_Map)
+        if (Eluna* e = m_Map->GetEluna())
+            e->OnBGDestroy(this, GetTypeID(), GetInstanceID());
 #endif
 
     // remove objects and creatures

src/server/game/Maps/MapInstanced.cpp

@@ -277,6 +277,11 @@ BattlegroundMap* MapInstanced::CreateBattleground(uint32 InstanceId, Battlegroun
 
     sScriptMgr->OnCreateMap(map);
 
+#ifdef ELUNA
+    if(Eluna* e = map->GetEluna())
+        e->OnBGCreate(bg, bg->GetTypeID(), bg->GetInstanceID());
+#endif
+
     return map;
 }
 

src/server/game/Scripting/ScriptMgr.cpp

@@ -1429,13 +1429,7 @@ void ScriptMgr::OnCreateMap(Map* map)
 
 #ifdef ELUNA
     if (Eluna* e = map->GetEluna())
-    {
         e->OnCreate(map);
-
-        if (map->IsBattlegroundOrArena())
-            if (Battleground* bg = map->ToBattlegroundMap()->GetBG())
-                e->OnBGCreate(bg, bg->GetTypeID(), bg->GetInstanceID());
-    }
 #endif
 
     SCR_MAP_BGN(WorldMapScript, map, itr, end, entry, IsWorldMap);