《Python Crash Course 2》Alien Invasion添加Bullet类后报错求助

我正在学习《Python Crash Course 2》，为Alien Invasion游戏添加Bullet类后出现报错。手动输入所有代码并与教程对比确认一致，但错误依旧存在。

报错信息：

AttributeError: 'AlienInvasion' object has no attribute 'screen_rect'

以下是我的alien_invasion.py代码：

import sys

import pygame

from settings import Settings

from ship import Ship
from bullet import Bullet


class AlienInvasion:
    """Overall class to manage assets and behavior."""

    def __init__(self):
        """Initialize the game, and create game resources."""
        pygame.init()
        self.settings = Settings()

        self.screen = pygame.display.set_mode((0, 0), pygame.FULLSCREEN)
        self.settings.screen_width = self.screen.get_rect().width
        self.settings.screen_height = self.screen.get_rect().height
        """self.screen = pygame.display.set_mode(
            (self.settings.screen_width, self.settings.screen_height))"""
        pygame.display.set_caption("Alien Invasion")

        self.ship = Ship(self)
        self.bullets = pygame.sprite.Group()

    def run_game(self):
        """start the main loop for the game."""
        while True:
            self._check_events()
            self.ship.update()
            self.bullets.update()
            self._update_screen()

    def _check_events(self):
        """Respond to key presses and mouse events."""
        for event in pygame.event.get():
            if event.type == pygame.QUIT:
                sys.exit()
            elif event.type == pygame.KEYDOWN:
                self._check_keydown_events(event)
            elif event.type == pygame.KEYUP:
                self._check_keyup_events(event)

    def _check_keydown_events(self, event):
        """Respond to key presses."""
        if event.key == pygame.K_RIGHT:
            self.ship.moving_right = True
        elif event.key == pygame.K_LEFT:
            self.ship.moving_left = True
        elif event.key == pygame.K_q:
            sys.exit()
        elif event.key == pygame.K_SPACE:
            self._fire_bullet()

    def _check_keyup_events(self, event):
        """Respond to key releases."""
        if event.key == pygame.K_RIGHT:
            self.ship.moving_right = False
        elif event.key == pygame.K_LEFT:
            self.ship.moving_left = False

    def _fire_bullet(self):
        """Create a new bullet and add it to the bullets group."""
        new_bullet = Bullet(self)
        self.bullets.add(new_bullet)

    def _update_screen(self):
        """Update images on the screen, and flip"""
        self.screen.fill(self.settings.bg_color)
        self.ship.blitme()
        for bullet in self.bullets.sprites():
            bullet.draw_bullet()

        pygame.display.flip()


if __name__ == '__main__':
    # Make a game instance, and run the game.
    ai = AlienInvasion()
    ai.run_game()

恳请各位帮忙排查错误原因，谢谢！

内容的提问来源于stack exchange，提问作者Purushottama V