Site Configurator - error in console after adding second image to Html Area

[sgauruseu]

1. Open Superhero site, open site configurator
2. Insert first image in HtmlArea
3. Close the modal dialog and open it again
4. Do scroll htmlarea, click in the space under the inserted picture.
5. Press the Insert Image menu item on the toolbar

Bug- modal dialog does not close and error appears in the console:

Uncaught TypeError: Cannot read property 'checkReadOnly' of undefined at $.insertElementIntoRange (_all.js:1) at $.insertElement (_all.js:1) at $.<anonymous> (_all.js:1) at a.m (_all.js:1) at a.<anonymous> (_all.js:1) at a.window.CKEDITOR.window.CKEDITOR.dom.CKEDITOR.editor.CKEDITOR.editor.fire (_all.js:1) at a.insertElement (_all.js:1) at p.finalizeCreation (_all.js:1) at CKEDITOR.dialog.e (_all.js:1) at CKEDITOR.dialog.a.(anonymous function) (http://localhost:8080/admin/tool/com.enonic.xp.app.contentstudio/main/_/asset/com.enonic.xp.app.contentstudio:1539092361/lib/_all.js:1:4385)

[ashklianko]

https://github.com/ckeditor/ckeditor-dev/issues/2517