报错信息：There was an unexpected error. Msg: TypeError: window is null
Url: chrome://selenium-ide/content/selenium-runner.js, line: 390, column: 7
createSelenium@chrome://selenium-ide/content/selenium-runner.js:390:7
start@chrome://selenium-ide/content/selenium-runner.js:405:16
Debugger.prototype.start@chrome://selenium-ide/content/debugger.js:154:3
Editor.prototype.playCurrentTestCase@chrome://selenium-ide/content/editor.js:925:3
Editor.controller.doCommand@chrome://selenium-ide/content/editor.js:387:9
goDoCommand@chrome://global/content/globalOverlay.js:100:7
oncommand@chrome://selenium-ide/content/selenium-ide.xul:1:1
原因 火狐浏览器关闭了
解决办法：打开火狐浏览器 进行录制回放