[Stability] Various crash fixes based on Regrad fixes and crashlogs. (#1928)

These contains various fixes, fixes that have history worked one in past
more then once as person as group, aswell @Wishmaster117. But due
various reasons we had to drop them due priority or simply timewise.
These fixes have recollected again by @Regrad based on his crash logs.

Most crash logs we have, i am talking 30+ of them, to many to post here.
@Regrad running a larger server 100+ real players with bots, which means
he will walk into issues that most of us wont or are extremely difficult
to reproduce.

@Regrad used LLM to solve them based on crash log and mentioned his
server crashes almost disappeared, instead of redoing every single PR
and pull them apart. I tried to keep his bunch of changes together as
whole, reviewed them, some redone, verified again etc etc. This is not
how would normally do this. But since i want @Regrad being able to
confirm, we need this in a package as a whole. Pulling them apart in the
current situation is simply to much, to complicated in the verification
process.

So this PR is open and in my opinion has priority above others, but
@Regrad is only person who can give the green light for the
mod-playerbot changes for now.

I, we spend huge amount of time into these issues over last couple of
months. I will put other PR's on hold for abit.

---------

Signed-off-by: Engardium <regradius@gmail.com>
Co-authored-by: Engardium <regradius@gmail.com>

src/Playerbots.cpp

@@ -124,24 +124,49 @@ public:
         }
     }
 
-    bool OnPlayerBeforeTeleport(Player* player, uint32 mapid, float /*x*/, float /*y*/, float /*z*/, float /*orientation*/, uint32 /*options*/, Unit* /*target*/) override
+    bool OnPlayerBeforeTeleport(Player* /*player*/, uint32 /*mapid*/, float /*x*/, float /*y*/, float /*z*/, float /*orientation*/, uint32 /*options*/, Unit* /*target*/) override
     {
-        // Only apply to bots to prevent affecting real players
-        if (!player || !player->GetSession()->IsBot())
+        /* for now commmented out until proven its actually required
+        * havent seen any proof CleanVisibilityReferences() is needed
+
+        // If the player is not safe to touch, do nothing
+        if (!player)
             return true;
 
-        // If changing maps, proactively clean visibility references to prevent
-        // stale pointers in other players' visibility maps during the teleport.
-        // This fixes a race condition where:
-        // 1. Bot A teleports and its visible objects start getting cleaned up
-        // 2. Bot B is simultaneously updating visibility and tries to access objects in Bot A's old visibility map
-        // 3. Those objects may already be freed, causing a segmentation fault
-        if (player->GetMapId() != mapid && player->IsInWorld())
-        {
-            player->GetObjectVisibilityContainer().CleanVisibilityReferences();
-        }
+        // If same map or not in world do nothing
+        if (!player->IsInWorld() || player->GetMapId() == mapid)
+            return true;
 
-        return true;  // Allow teleport to continue
+        // If real player do nothing
+        PlayerbotAI* ai = GET_PLAYERBOT_AI(player);
+        if (!ai || ai->IsRealPlayer())
+            return true;
+
+        // Cross-map bot teleport: defer visibility reference cleanup.
+        // CleanVisibilityReferences() erases this bot's GUID from other objects' visibility containers.
+        // This is intentionally done via the event queue (instead of directly here) because erasing
+        // from other players' visibility maps inside the teleport call stack can hit unsafe re-entrancy
+        // or iterator invalidation while visibility updates are in progress
+        ObjectGuid guid = player->GetGUID();
+        player->m_Events.AddEventAtOffset(
+            [guid, mapid]()
+            {
+                // do nothing, if the player is not safe to touch
+                Player* p = ObjectAccessor::FindPlayer(guid);
+                if (!p || !p->IsInWorld() || p->IsDuringRemoveFromWorld())
+                    return;
+
+                // do nothing if we are already on the target map
+                if (p->GetMapId() == mapid)
+                    return;
+
+                p->GetObjectVisibilityContainer().CleanVisibilityReferences();
+            },
+            Milliseconds(0));
+
+        */
+
+        return true;
     }
 
     void OnPlayerAfterUpdate(Player* player, uint32 diff) override