Core/Spell: Properly remove REACT_PASSIVE on permanent feign death unapply. Fixes and closes #21156.

(cherry picked from commit ac8b9be5d67ccaba3f51663eeccca60ae86cea5b)

src/server/scripts/Spells/spell_generic.cpp

@@ -1043,8 +1043,8 @@ class spell_gen_creature_permanent_feign_death : public AuraScript
         target->AddDynamicFlag(UNIT_DYNFLAG_DEAD);
         target->AddUnitFlag2(UNIT_FLAG2_FEIGN_DEATH);
 
-        if (target->GetTypeId() == TYPEID_UNIT)
-            target->ToCreature()->SetReactState(REACT_PASSIVE);
+        if (Creature* creature = target->ToCreature())
+            creature->SetReactState(REACT_PASSIVE);
     }
 
     void OnRemove(AuraEffect const* /*aurEff*/, AuraEffectHandleModes /*mode*/)
@@ -1052,6 +1052,9 @@ class spell_gen_creature_permanent_feign_death : public AuraScript
         Unit* target = GetTarget();
         target->RemoveDynamicFlag(UNIT_DYNFLAG_DEAD);
         target->RemoveUnitFlag2(UNIT_FLAG2_FEIGN_DEATH);
+
+        if (Creature* creature = target->ToCreature())
+            creature->InitializeReactState();
     }
 
     void Register() override