django-ajax-select | Enables editing of ForeignKey , ManyToMany | Autocomplete library

In short: django-ajax-selects works fine with filtering existing items, but gives JS error by adding new item.

Details. Using Django 3.1. At Admin site one needs to create object of model Choice with ForeignField to model Question. Django-ajax-selects (DAS) is used to populate the field (dynamic filtering). By typing letters DAS handles the queryset and outputs the list of relevant questions. One can choose a question from the list and save new Choice. All this works fine.

If no proper questions by typing are found then one can click +add button and add new question in popup window with form. After clicking 'Save' according to DAS docs:

1. new question must be saved into the database;
2. popup window must be closed;
3. the edited field must be populated with new question .

Screenshot with popup window

The problem is that Django stops at step2: new question is created, the popup window is getting blank and doesn't close with "Popup closing ..." in the head. There is an JS error in the window: