链表中删除节点操作引发异常：读取访问权限冲突

bool Clear(long long _ticketsnum)//删除节点
    {
        Node* current = head, * s;
        while (current)
        {
            if (current->link->data.ticketsnum == _ticketsnum)
            {
                s = current->link;
                current->link = s->link;
                delete s;
                return true;
            }
            current = current->link;
        }
        return false;
    }

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