将用户添加到 sqlite3 数据库

我在不和谐中有自己的机器人，如果用户不在数据库中，那么他必须在那里输入，但我无法在 on_message 事件中弄清楚如何做到这一点。

@bot.event
async def on_message(message):
    if cursor.execute(f"SELECT id FROM users WHERE id = {message.author.id}").fetchone()[0] is None:
        cursor.execute(f"INSERT INTO users VALUES ({message.author.id}, 100, 'Нету', 0, 0)")
        conn.commit()
        cursor.execute(f"INSERT INTO inventory VALUES ({message.guild.id}, {message.author.id}, '')")


    else:
        pass
    bot.process_commands(message)

检查用户是否有 id 时出错。但是如果它抛出错误，我如何检查它是否为 None

Traceback (most recent call last):
  File "C:\Users\semnf\AppData\Local\Programs\Python\Python310\lib\site-packages\discord\client.py", line 343, in _run_event
    await coro(*args, **kwargs)
  File "c:\Users\semnf\OneDrive\Рабочий стол\DiscBot\hello.py", line 62, in on_message
    if cursor.execute(f"SELECT id FROM users WHERE id = {message.author.id}").fetchone()[0] is None:
TypeError: 'NoneType' object is not subscriptable