没有关于滚动条操作的封装，使用JS命令滑倒浏览器底部报错

<p><img src="http://talk-cdn.liumatest.cn/74ab5ae2-3c1d-4264-9217-bb54550ce903.png" style="max-width:100%;"></p><blockquote><p>'NoneType' object is not iterable<br><br>程序错误信息: <br>Traceback (most recent call last):<br> File "C:\Users\creating-main\AppData\Local\Programs\Python\Python38\lib\unittest\case.py", line 60, in testPartExecutor<br> yield<br> File "C:\Users\creating-main\AppData\Local\Programs\Python\Python38\lib\unittest\case.py", line 676, in run<br> self._callTestMethod(testMethod)<br> File "C:\Users\creating-main\AppData\Local\Programs\Python\Python38\lib\unittest\case.py", line 633, in _callTestMethod<br> method()<br> File "C:\Users\creating-main\Desktop\engine\lm\lm_case.py", line 29, in testEntrance<br> WebTestCase(test=self).execute()<br> File "C:\Users\creating-main\Desktop\engine\core\web\testcase.py", line 31, in execute<br> self.loop_execute(self.case_message['optList'], [])<br> File "C:\Users\creating-main\Desktop\engine\core\web\testcase.py", line 76, in loop_execute<br> raise e<br> File "C:\Users\creating-main\Desktop\engine\core\web\testcase.py", line 64, in loop_execute<br> step.execute()<br> File "C:\Users\creating-main\Desktop\engine\core\web\teststep.py", line 39, in execute<br> self.result = func(self.test, self.driver, **opt_content)<br> File "C:\Users\creating-main\Desktop\engine\core\web\find_opt.py", line 98, in execute_script<br> Browser(test, driver).execute_script(kwargs["data"]["script"], tuple(kwargs["data"]["arg"]))<br>TypeError: 'NoneType' object is not iterable<br></p></blockquote>