Python 垃圾回收机制中，重复实例化对象会触发__del__方法，为什么这会导致异常？

import socket
import pymysql

class mydb(object):
    def __init__(self, name):
        self.conn = pymysql.connect()
        self.cursor = self.conn.cursor()
        print(name, '初始化了mydb类')
    def __del__(self):
        print('销毁连接', self.name)
        self.cursor.close()
        self.conn.close()
    def query(str) -> str | int | exception:
        pass
    def add(str) -> int | str | exception:
        pass

class socketsetting(object):
    def __init__(self, name):
        print(name)
        self.db = mydb(name)

class myoption(object):
    def __init__(self, name):
        self.socket = socketsetting(name)

class run(object):
    def __init__(self):
        self.setting = socketsetting('setting1')
        self.setting = socketsetting('setting2')
        self.setting = socketsetting('setting3')

if __name__ == '__main__':
    run = run()

def __del__(self):
    print('销毁连接', self.name)
    if self.db:
        self.db.cursor.close()
        self.db.conn.close()