Error script when adding data on tinyMCE

Description

Steps to reproduce:

1. Create and publish a configurable view that allows editors to create Editional blocks (that is, blocks having TinyMCE). 
2. Open the view on CM.
3. Add new > Enter required field. 
4. Enter data to Mainbody (TinyMCE property)
5. Click Save.

Steps to reproduce in CMS:

1. In Edit Mode, create a block of type Editorial
2. Add the new created block to the Large content area of the Start page
3. Use Quick Edit to edit the editorial block
4. Add some text then click Save

Actual result:

Error script : widgets.js:2 Uncaught TypeError: Cannot read property 'tagName' of null
at Object.set (widgets.js:2)
at Object._onChange (widgets.js:2)
at Object.<anonymous> (widgets.js:2)
at widgets.js:2

Expected result:

No error script.