《飞机大战》pygame异常报错信息：NameError: name ' ' is not defined，名称错误，名称“ ”未定义

准备在游戏页面添加一个历史最高分的显示，在关卡得分和关卡等级后面，recordscore 在这之前还没有定义，直接做了一个 global recordscore 全局变量，但是还是报错；
报错信息如下：

pygame 1.9.6
Hello from the pygame community. https://www.pygame.org/contribute.html
Traceback (most recent call last):
  File "G:/plane/main.py", line 539, in <module>
    main()
  File "G:/plane/main.py", line 463, in main
    record_score_text = score_font.render("历史最高分: %d" % recordscore, True, WHITE)
NameError: name 'recordscore' is not defined

代码：

            if life_num:
                for i in range(life_num):
                    screen.blit(life_image, \
                                (width - 10 - (i + 1) * life_rect.width, \
                                 height - 10 - life_rect.height))

            score_text = score_font.render(str("本关卡得分: %s" % score), True, WHITE)
            screen.blit(score_text, (10, 5))
            level1_text = level1_font.render("关卡等级:%s "% level, True, WHITE)
            screen.blit(level1_text, (10, 40))
            record_score_text = score_font.render("历史最高分: %d" % recordscore, True, WHITE)
            screen.blit(record_score_text, (10, 60))
        elif life_num == 0:
            pygame.mixer.music.stop()
            pygame.mixer.stop()

            # 停止发放补给
            pygame.time.set_timer(SUPPLY_TIME, 0)

            if not recorded:
                recorded = True
                # 读取历史最高分
                with open("record.txt", "r") as f:
                    recordscore = int(f.read())

                if score > recordscore:
                    with open("record.txt", "w") as f:
                        f.write(str(score))
            # 绘制结束画面
            record_score_text = score_font.render("Best: %d" % recordscore, True, WHITE)
            screen.blit(record_score_text, (50, 50))