在加入scrollbar的时候，从最下方快速拉到最上方会有报错

[pitaya-V]

KeyNotFoundException: The given key was not present in the dictionary. System.Collections.Generic.Dictionary2[System.Int32,UnityEngine.RectTransform].get_Item (Int32 key) (at /Users/builduser/buildslave/mono/build/mcs/class/corlib/System.Collections.Generic/Dictionary.cs:150) GridScroller.ChangeToIndex (Int32 from, Int32 to) (at Assets/Scripts/UI/UIBase/GridScroller.cs:248) GridScroller.SwapIndex (Int32 startIndex) (at Assets/Scripts/UI/UIBase/GridScroller.cs:235) GridScroller.OnValueChanged (Vector2 normalizedPosition) (at Assets/Scripts/UI/UIBase/GridScroller.cs:210) UnityEngine.Events.InvokableCall1[UnityEngine.Vector2].Invoke (Vector2 args0) (at D:/unity/Runtime/Export/UnityEvent.cs:207) UnityEngine.Events.UnityEvent`1[UnityEngine.Vector2].Invoke (Vector2 arg0) (at D:/unity/Runtime/Export/UnityEvent_1.cs:58) UnityEngine.UI.ScrollRect.LateUpdate () (at D:/unity/Extensions/guisystem/UnityEngine.UI/UI/Core/ScrollRect.cs:434)