Почему появляется ошибка AttributeError: 'NoneType' object has no attribute 'cursor'

Почему появляется ошибка AttributeError: 'NoneType' object has no attribute 'cursor' Пишу бот с регистрацией и бд и возникла ошибка AttributeError: 'NoneType' object has no attribute 'cursor' Вот мой код

import sqlite3

class Database: def init(self, db_file): self.connection = None var = self.connection == sqlite3.connect(db_file) self.cursor = self.connection.cursor()

def add_user(self, user_id):
    with self.connection:
        return self.cursor.execut("INSERT INTO `users` (users.users.user_id) VALUES (?)", (user_id,))


def user_exists(self, user_id):
    with self.connection:
        result = self.cursor.execute("SELECT * FROM `users` WHERE `user_id`= ?", (user_id)).fetchall()
        return bool(len(result))

def set_nickname(self, user_id, nickname):
    with self.connection:
        return self.cursor.execute("UPDATE `users` SET `nickname` = ? WHERE `user_id` = ?", (nickname, user_id,))

def get_signup(self, user_id):
    with self.connection:
        result = self.cursor.execute("SELECT `signup` FROM `users` WHERE `user_id` = ?",(user_id,)).fetchall()
        for row in result:
            signup = str(row[0])
        return signup
def set_signup(self, user_id, signup):
    with self.connection:
        return self.cursor.execute('UPDATE `users` SET `signup` = ? WHERE `user_id` = ?', (signup, user_id,))