■ItemManager.cs

Start内を下記に直す

textures = Resources.LoadAll<Sprite>("ItemTityPotions");
Slots = GameObject.Find("Slots");
bokking = GameObject.Find("Ethan").GetComponent<Playerbokking>();
GameObject slotPrefab = (GameObject)Resources.Load("itemSlotPrefab");

ItemSlot.setItemIcon (textures);
ItemSlot.setItemManager (this);

for (int i = 0; i < 100; i++)
{
GameObject slot = Instantiate(slotPrefab);
slot.transform.SetParent(Slots.transform);
ItemSlot itemSlot = slot.GetComponent<ItemSlot> ();
itemSlotList.Add(itemSlot);
}

終わり