Custom Query

Steps to reproduce

1. Consider this jsFiddle: ​https://jsfiddle.net/12o9kyr6/
2. Switch to source mode.

3 Delete all contents.

4. Switch back to WYSIWYG mode, but don't focus the editor.
5. Click any of the combo boxes.

Expected result

Combo box is opened, no error thrown.

Actual result

Combo box is opened, but an error is thrown:

Uncaught TypeError: Cannot read property 'blockLimit' of null
    at CKEDITOR.style.checkApplicable (ckeditor.js:484)
    at $.onOpen (ckeditor.js:980)
    at $.e.onShow (ckeditor.js:787)
    at $.showBlock (ckeditor.js:692)
    at Object.execute (ckeditor.js:784)
    at $.<anonymous> (ckeditor.js:784)
    at ckeditor.js:31
    at Object.callFunction (ckeditor.js:31)
    at HTMLAnchorElement.onclick ((index):1)

Other details (browser, OS, CKEditor version, installed plugins)

This is a mirror of a ticket in Drupal: ​https://www.drupal.org/node/2785483

The problem here is that features added through addCommand assume that the content they allow will remain that way, but it's possible to override that using the config.

Steps to reproduce

1. Disable removing empty spans (this feature is important because spans retain the formatting)
2. Copy table with empty cells
3. Try to set cursor in the empty cell

Expected result

Need give an opportunity to put the cursor in the cell.

Actual result

Can't set cursor in the cell

Other details (browser, OS, CKEditor version, installed plugins)