ExportMenu selectedColumns warning

[afortiexchange]

Prerequisites

• [x] I have searched for similar issues in both open and closed tickets and cannot find a duplicate.
• [x] The issue still exists against the latest master branch of yii2-export.
• [x] This is not an usage question. I confirm having gone through and read the documentation and demos.
• [x] This is not a general programming / coding question. (Those should be directed to the webtips Q & A forum).
• [x] 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

1. Run ExportMenu widget

Expected behavior and actual behavior

When I follow those steps, I see...

Warning in_array() expects parameter 2 to be array, null given 1227 $isNoExport = in_array($key, $this->noExportColumns) || !in_array($key, $this->selectedColumns);

I was expecting...

See working widget. ;-) I suppose default value for $selectedColumns property in kartik\export\ExportMenu shoukd be empty array.

vendor/kartik-v/yii2-export/src/ExportMenu.php:256 public $selectedColumns = [];

Environment

php 7.2.7-1+0~20180622080852.23+jessie~1.gbpfd8e2e Linux vbox 3.16.0-5-686-pae #1 SMP Debian 3.16.51-3+deb8u1 (2018-01-08) i686

Browsers

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

Operating System

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

Libraries

• jQuery version:
• yii2-export version: v1.3.7

Isolating the problem

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

[kartik-v]

Duplicate to and resolved via #284.