(De)Publish all in folder dialog cannot be closed

Broken publish / unpublish of a folder:

When trying to publish or unpublish any folder which contains one or more documents
The user is unable to close the dialog when they have finished.
Neither "Done" nor "[x]" are working
No exception logged in the CMS
A Wicket exception is logged in the browser console
The user can only refresh the page to get rid of this dialog

wicket-ajax-jquery-ver-1601490891000.js:1 Wicket.Ajax:  FunctionsExecuter.processNext: TypeError: Cannot set property 'disabled' of null
error @ wicket-ajax-jquery-ver-1601490891000.js:1