求问这段代码为何报错？（osx系统anaconda python3)

import pygame
import sys
def run_game():
pygame.init()
screen=pygame.display.set_mode((1200,800))
pygame.display.set_caption("Alien Invasion")
while True:
for event in pygame.event.get():
if event.type == pygame.QUIT:
sys.exit()
pygame.display.flip()
run_game()

报错：An exception has occurred, use %tb to see the full traceback.

SystemExit

运行%tb后：

https://blog.csdn.net/yapingge2014/article/details/52101287/