Javascript error thrown when document with OpenUIStringField is added to project

Steps to reproduce:

1. Go to hap, xmas tree document
2. Select project->Add to project
3. See console log

Expected result:
No console error

Actual result: 
Uncaught (in promise) Error: Connection destroyed
at w (penpal.min-ver-1562198516000.js:1)
at e.forEach.e (penpal.min-ver-1562198516000.js:1)
at Array.forEach (<anonymous>)
at Object.destroy (penpal.min-ver-1562198516000.js:1)
at HippoAjax.registerDestroyFunction (OpenUiBehavior-ver-1562198516000.js:33)
at YAHOO.hippo.HippoAjaxImpl.callDestroyFunction (hippoajax-min-ver-1562198502000.js:1)
at YAHOO.hippo.HippoAjaxImpl.cleanupElement (hippoajax-min-ver-1562198502000.js:1)
at HTMLDocument.<anonymous> (hippoajax-min-ver-1562198502000.js:1)
at HTMLDocument.dispatch (jquery-1.12.4-ver-1562198504000.js:3)
at HTMLDocument.r.handle (jquery-1.12.4-ver-1562198504000.js:3)

Regression versus 13.1.4 (It does not reproduce there)

 Also, it slows down the automated tests, since when doing this action in the status I see connecting, and waiting on the application to finish a task.