GList.AddItemFromPool报错

报错代码：GObject obj = container.AddItemFromPool(commonIconPath);
报错log：
NullReferenceException: Object reference not set to an instance of an object
FairyGUI.DisplayObject.UpdateHierarchy () (at D:/FairyGUI-unity/Scripts/Core/DisplayObject.cs:1435)
FairyGUI.DisplayObject.InternalSetParent (FairyGUI.Container value) (at D:/FairyGUI-unity/Scripts/Core/DisplayObject.cs:840)
FairyGUI.Container.AddChildAt (FairyGUI.DisplayObject child, System.Int32 index) (at D:/FairyGUI-unity/Scripts/Core/Container.cs:144)
FairyGUI.GComponent.ChildStateChanged (FairyGUI.GObject child) (at D:/FairyGUI-unity/Scripts/UI/GComponent.cs:732)
FairyGUI.GComponent.AddChildAt (FairyGUI.GObject child, System.Int32 index) (at D:/FairyGUI-unity/Scripts/UI/GComponent.cs:214)
FairyGUI.GList.AddChildAt (FairyGUI.GObject child, System.Int32 index) (at D:/FairyGUI-unity/Scripts/UI/GList.cs:350)
FairyGUI.GComponent.AddChild (FairyGUI.GObject child) (at D:/FairyGUI-unity/Scripts/UI/GComponent.cs:172)
FairyGUI.GList.AddItemFromPool (System.String url) (at D:/FairyGUI-unity/Scripts/UI/GList.cs:339)
ClientRewardListTool.GetShowOneItemList (System.Int32 showItem, System.Int32 showNum, FairyGUI.GList container, System.Boolean showTips) (at Assets/Script/Data/ClientData/ClientItemData.cs:565)


这个报错不是必现的，一般程序刚启动没问题，操作一段时间后有概率会报这个错误