item undo bug

[RogerLiu-Yuxuan]

In match.py:

The undo function is defined by the following script.

def undo(self, event: Event):
assert event.after_id == 0 or event.before_id == 0
item_id = event.before_id or event.after_id
prev = None
while prev is None or prev.item_id != item_id:
prev = self._events.pop()
if prev.type == "ITEM_PURCHASED":
self.destroy(prev.item_id)
elif prev.type == "ITEM_DESTROYED":
self.add(prev.item_id)
elif prev.type == "ITEM_SOLD":
self.add(prev.item_id)
else:
raise TypeError(f"Unexpected event type {prev.type}")

The event of synthetic an item is down by destroying the previous item first and then purchasing a new item. If an undo event happens to this item, the item will be destroyed directly. However, the correct undo of synthetic is disassembled this item.