Use the delete method of Set or WeakSet Proxy maybe be modfiied！

[Jinuss]

as below, it`s that rewrite the delete method of Map or Set in reactive package.

packages\reactivity\src\collectionHandlers.ts

  delete(this: CollectionTypes, key: unknown) {
            const target = toRaw(this)
            const { has, get } = getProto(target)
            let hadKey = has.call(target, key)
            if (!hadKey) {
              key = toRaw(key)
              hadKey = has.call(target, key)
            } else if (__DEV__) {
              checkIdentityKeys(target, has, key)
            }

            const oldValue = get ? get.call(target, key) : undefined
            // forward the operation before queueing reactions
            const result = target.delete(key)
            if (hadKey) {
              trigger(target, TriggerOpTypes.DELETE, key, undefined, oldValue)
            }
            return result
 }

I think mabye it is a mistake, if the proxy instance is Set or WeakSet type, we should set the oldValue is the key rather than undefined