Core/Entities: allow guardian pets to inherit spellmods

src/server/game/Entities/Unit/Unit.cpp

@@ -13210,13 +13210,13 @@ Player* Unit::GetSpellModOwner() const
     if (Player* player = const_cast<Unit*>(this)->ToPlayer())
         return player;
 
-    if (IsPet() || IsTotem())
+    if (HasUnitTypeMask(UNIT_MASK_PET | UNIT_MASK_TOTEM | UNIT_MASK_GUARDIAN))
     {
         if (Unit* owner = GetOwner())
             if (Player* player = owner->ToPlayer())
                 return player;
     }
-    return NULL;
+    return nullptr;
 }
 
 ///----------Pet responses methods-----------------