我设置了代理，但是代理有时会过期，因此它会使init驱动程序失败。然后，驱动程序为None，因此无法关闭打开的Firefox。
try:
driver=Firefox(firefox_options=firefox_options, firefox_profile=firefox_profile)
driver.set_page_load_timeout(50)
self.driver =driver
except Excetion as e:
print("init erro")
finally:
self.driver.quit() ## self.driver is None,can't shutdown the firefox client