Fix error in CkEditor v6 [#3370631]

This is a duplicate of this issue which is tagged as version 5 and already marked as RTBC.

Opening an issue to create & test a PR for version 6.

Show commands

Start within a Git clone of the project using the version control instructions.

Add & fetch this issue fork’s repository

Or, if you do not have SSH keys set up on git.drupalcode.org:

Add & fetch this issue fork’s repository

6.0.x changes, plain diff MR !26
Check out this branch for the first time

Check out existing branch, if you already have it locally
3370631-fix-error-in changes, plain diff MR !25
Check out this branch for the first time

Check out existing branch, if you already have it locally