Element: [Bug Report] in MessageBox component, if it is not closed by button, it will cause errors.

[atzcl]

Element UI version

2.4.6

OS/Browsers version

Mac 10.13 / Chrome 68

Vue version

2.5.17

Reproduction Link

https://jsfiddle.net/api/post/library/pure/

Steps to reproduce

【 在 jsfiddle 中无法重现，但是在官网上面的示例是可以重现的：http://element.eleme.io/#/zh-CN/component/message-box 】
使用 MessageBox 组件，通过点击遮罩层、ESC 快捷键关闭弹窗，控制台报错：common.js:67 Uncaught (in promise) {message: "The message port closed before a response was received."} Error in event handler for runtime.onMessage: TypeError: Cannot read property 'isVisible' of undefined

What is Expected?

无报错

What is actually happening?

【 在 jsfiddle 中无法重现，但是在官网上面的示例是可以重视的：http://element.eleme.io/#/zh-CN/component/message-box 】
控制台报错：common.js:67 Uncaught (in promise) {message: "The message port closed before a response was received."} Error in event handler for runtime.onMessage: TypeError: Cannot read property 'isVisible' of undefined

[element-bot]

Translation of this issue:

Element UI version
2.4.6

OS/Browsers version
Mac 10.13 / Chrome 68

Vue version
2.5.17

Reproduction Link
https://jsfiddle.net/api/post/library/pure/

Steps to reproduce
[cannot be reproduced in jsfiddle, but the example on the official website is reproducible: http://element.eleme.io/#/zh-CN/component/message-box]

Using the MessageBox component, the console reports an error by clicking the masking layer and the ESC shortcut key to close the pop-up window: common.js: 67 Uncaught (in promise) {message: The message port closed before a response was received.'} ``Error in event handler for runtime. onMessage: TypeError: Cannot read property'is Visible'of Undefined
What is Expected?

No mistake
What is actually happening?

[cannot be reproduced in jsfiddle, but the example on the official website is important: http://element.eleme.io/#/zh-CN/component/message-box]
Console error: common.js: 67 Uncaught (in promise) {message: The message port closed before a response was received.'} ``Error in event handler for runtime.onMessage: TypeError: Cannot read property'is Visible' of undefined

[element-bot]

Hi, your JSFiddle page is blank because it seems you forgot to click the Save button. Please save your fiddle and then edit this issue with the new link.

[ziyoung]

无法重现。

[atzcl]

@ziyoung 刚刚在官网重试了下，依然存在。

[ziyoung]

你那个报错的消息来自于浏览器插件，不是 element-ui 本身的 bug。你用隐身模式打开再试一下。