export to json happen javascript error

[haohetao]

Prerequisites

• I have searched for similar issues in both open and closed tickets and cannot find a duplicate.
• The issue still exists against the latest master branch of yii2-grid.
• This is not an usage question. I confirm having gone through and read the documentation and demos.
• This is not a general programming / coding question. (Those should be directed to the webtips Q & A forum).
• I have attempted to find the simplest possible steps to reproduce the issue.
• I have included a failing test as a pull request (Optional).

Steps to reproduce the issue

Expected behavior and actual behavior

When I follow those steps, I see...

I was expecting...

Environment

Browsers

• [x ] Google Chrome
• Mozilla Firefox
• Internet Explorer
• Safari

Operating System

• [ x] Windows
• Mac OS X
• Linux
• Mobile

Libraries

• jQuery version:
• yii2-grid version:

Isolating the problem

• This bug happens on the demos page
• The bug happens consistently across all tested browsers
• [ x] This bug happens when using yii2-grid without other plugins.

kv-grid-export.js:116 Uncaught TypeError: Cannot read property 'slugColHeads' of undefined
at HTMLTableCellElement. (kv-grid-export.js:116)
at Function.each (jquery.js:367)
at jQuery.fn.init.each (jquery.js:202)
at GridExport.getArray (kv-grid-export.js:114)
at GridExport.exportJSON (kv-grid-export.js:359)
at kv-grid-export.js:150

[haohetao]

d1cf316#diff-8251c57ea05d8f626a339f2c8a572ba3
delete ".$h" is ok

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[mcserep]

I have the same bug after upgrading yii2-grid from version 3.1.7 to 3.3.4.