Core/Scripts: Fixed ENSURE_AI assertion failures when used in Reset()/InitializeAI() hooks with hotswap

Updates #20727

(cherry picked from commit 2fd9dc2edb0355d15f5afd21cc6aa61d172d19cc)

3 files changed, 17 insertions, 3 deletions

diff --git a/src/server/game/Entities/Creature/Creature.cpp b/src/server/game/Entities/Creature/Creature.cpp
index e6b604d074a..8e9f41296f7 100644
--- a/src/server/game/Entities/Creature/Creature.cpp
+++ b/src/server/game/Entities/Creature/Creature.cpp
@@ -811,7 +811,7 @@ bool Creature::AIM_Destroy()
     return true;
 }
 
-bool Creature::AIM_Initialize(CreatureAI* ai)
+bool Creature::AIM_Create(CreatureAI* ai /*= nullptr*/)
 {
     // make sure nothing can change the AI during AI update
     if (m_AI_locked)
@@ -825,12 +825,23 @@ bool Creature::AIM_Initialize(CreatureAI* ai)
     Motion_Initialize();
 
     i_AI = ai ? ai : FactorySelector::selectAI(this);
+}
 
+void Creature::AI_InitializeAndEnable()
+{
     IsAIEnabled = true;
     i_AI->InitializeAI();
     // Initialize vehicle
     if (GetVehicleKit())
         GetVehicleKit()->Reset();
+}
+
+bool Creature::AIM_Initialize(CreatureAI* ai)
+{
+    if (!AIM_Create(ai))
+        return false;
+
+    AI_InitializeAndEnable();
     return true;
 }
 
diff --git a/src/server/game/Entities/Creature/Creature.h b/src/server/game/Entities/Creature/Creature.h
index b5ee31479b8..8b4a6a9b0ab 100644
--- a/src/server/game/Entities/Creature/Creature.h
+++ b/src/server/game/Entities/Creature/Creature.h
@@ -131,7 +131,9 @@ class TC_GAME_API Creature : public Unit, public GridObject<Creature>, public Ma
         bool IsEvadingAttacks() const { return IsInEvadeMode() || CanNotReachTarget(); }
 
         bool AIM_Destroy();
-        bool AIM_Initialize(CreatureAI* ai = NULL);
+        bool AIM_Create(CreatureAI* ai = nullptr);
+        void AI_InitializeAndEnable();
+        bool AIM_Initialize(CreatureAI* ai = nullptr);
         void Motion_Initialize();
 
         CreatureAI* AI() const { return reinterpret_cast<CreatureAI*>(i_AI); }
diff --git a/src/server/game/Scripting/ScriptMgr.cpp b/src/server/game/Scripting/ScriptMgr.cpp
index f8ef25e7b57..2367e26218c 100644
--- a/src/server/game/Scripting/ScriptMgr.cpp
+++ b/src/server/game/Scripting/ScriptMgr.cpp
@@ -453,7 +453,7 @@ class CreatureGameObjectAreaTriggerScriptRegistrySwapHooks
         if (creature->IsAlive())
             creature->ClearUnitState(UNIT_STATE_EVADE);
 
-        bool const created = creature->AIM_Initialize();
+        bool const created = creature->AIM_Create();
         ASSERT(created,
                "Creating the AI should never fail here!");
         (void)created;
@@ -464,6 +464,7 @@ class CreatureGameObjectAreaTriggerScriptRegistrySwapHooks
         if (!creature->IsAlive())
             return;
 
+        creature->AI_InitializeAndEnable();
         creature->AI()->EnterEvadeMode();
 
         // Cast a dummy visual spell asynchronously here to signal