Core/Battlegrounds: Fix possible shutdown crash

Closes #30725

3 files changed, 17 insertions, 7 deletions

diff --git a/src/server/game/Battlegrounds/Battleground.cpp b/src/server/game/Battlegrounds/Battleground.cpp
index bb08efda239..9176eaf430a 100644
--- a/src/server/game/Battlegrounds/Battleground.cpp
+++ b/src/server/game/Battlegrounds/Battleground.cpp
@@ -157,6 +157,12 @@ Battleground::~Battleground()
         m_Map->SetBG(nullptr);
         m_Map = nullptr;
     }
+
+    // Clear Group::m_bgGroup, Group might later reference it in its own destructor
+    for (Group* bgRaid : m_BgRaids)
+        if (bgRaid)
+            bgRaid->SetBattlegroundGroup(nullptr);
+
     // remove from bg free slot queue
     RemoveFromBGFreeSlotQueue();
 
diff --git a/src/server/game/Battlegrounds/Battleground.h b/src/server/game/Battlegrounds/Battleground.h
index e22e749aae6..eec41ece00b 100644
--- a/src/server/game/Battlegrounds/Battleground.h
+++ b/src/server/game/Battlegrounds/Battleground.h
@@ -325,6 +325,7 @@ class TC_GAME_API Battleground
 
         void AddToBGFreeSlotQueue();                        //this queue will be useful when more battlegrounds instances will be available
         void RemoveFromBGFreeSlotQueue();                   //this method could delete whole BG instance, if another free is available
+        void RemoveFromBGFreeSlotQueueOnShutdown() { m_InBGFreeSlotQueue = false; }
 
         void DecreaseInvitedCount(uint32 team)      { (team == ALLIANCE) ? --m_InvitedAlliance : --m_InvitedHorde; }
         void IncreaseInvitedCount(uint32 team)      { (team == ALLIANCE) ? ++m_InvitedAlliance : ++m_InvitedHorde; }
diff --git a/src/server/game/Battlegrounds/BattlegroundMgr.cpp b/src/server/game/Battlegrounds/BattlegroundMgr.cpp
index 9dc3abf8328..1aed0a37074 100644
--- a/src/server/game/Battlegrounds/BattlegroundMgr.cpp
+++ b/src/server/game/Battlegrounds/BattlegroundMgr.cpp
@@ -70,6 +70,10 @@ BattlegroundMgr::~BattlegroundMgr()
 
 void BattlegroundMgr::DeleteAllBattlegrounds()
 {
+    for (auto& [_, data] : bgDataStore)
+        for (Battleground* battleground : data.BGFreeSlotQueue)
+            battleground->RemoveFromBGFreeSlotQueueOnShutdown();
+
     bgDataStore.clear();
 }
 
@@ -904,13 +908,12 @@ void BattlegroundMgr::AddToBGFreeSlotQueue(BattlegroundTypeId bgTypeId, Battlegr
 
 void BattlegroundMgr::RemoveFromBGFreeSlotQueue(BattlegroundTypeId bgTypeId, uint32 instanceId)
 {
-    BGFreeSlotQueueContainer& queues = bgDataStore[bgTypeId].BGFreeSlotQueue;
-    for (BGFreeSlotQueueContainer::iterator itr = queues.begin(); itr != queues.end(); ++itr)
-        if ((*itr)->GetInstanceID() == instanceId)
-        {
-            queues.erase(itr);
-            return;
-        }
+    if (BattlegroundData* battlegroundData = Trinity::Containers::MapGetValuePtr(bgDataStore, bgTypeId))
+    {
+        auto itr = std::ranges::find(battlegroundData->BGFreeSlotQueue, instanceId, [](Battleground const* bg) { return bg->GetInstanceID(); });
+        if (itr != battlegroundData->BGFreeSlotQueue.end())
+            battlegroundData->BGFreeSlotQueue.erase(itr);
+    }
 }
 
 void BattlegroundMgr::AddBattleground(Battleground* bg)