I can confirm this issue. I've tried two earlier mentioned AS versions
from github and also change manually javascript files but no success.
$$("#admin__admins-update-2-form a.cancel").first().link return
undefined value. I wonder if .link is attribute introduced by "pure"
javascript, prototype or just active scaffold js? I found one place
where value is set to .link attribute. It's in function
register_cancel_hooks:

  register_cancel_hooks: function() {
    // anything in the insert with a class of cancel gets the closer
method, and a reference to this object for good measure
    var self = this;
    this.adapter.select('.cancel').each(function(elem) {
      elem.observe('click', this.close_handler.bind(this));
      elem.link = self;
    }.bind(this))
  },

It looks like .link is some helper attribute used only by AS but isn't
properly set. Can anyone fix it please?

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