fails in shopify theme edit

[Glen Pearl]

Describe the bug
A clear and concise description of what the bug is.

To Reproduce
Steps to reproduce the behavior:

1. Go to in your theme editor and try to scroll or click for more

Ajaxinate.prototype.loadMore = function getTheHtmlOfTheNextPageWithAnAjaxRequest() {
  this.request = new XMLHttpRequest();
  this.request.onreadystatechange = function success() {
    if (this.request.readyState === 4 && this.request.status === 200) {
      var parser = new DOMParser();
      var htmlDoc = parser.parseFromString(this.request.responseText, "text/html");
      var newContainer = htmlDoc.querySelectorAll(this.settings.container)[0];
      var newPagination = htmlDoc.querySelectorAll(this.settings.pagination)[0];
      this.containerElement.insertAdjacentHTML('beforeend', newContainer.innerHTML);
      this.paginationElement.innerHTML = newPagination.innerHTML;
      if (this.settings.callback && typeof this.settings.callback === 'function') {
        this.settings.callback(this.request.responseXML);
      }
      this.initialize();
    }
  }.bind(this);
  this.request.open('GET', this.nextPageUrl, false);
  this.request.send();
};

this doesn't seem to fix the issue as suggested, I even saw the code from the demo and tested that, Shopify has been updating things in the admin area so I'm not certain if this could be the underlying issues, I used to have no issues with ajaxinate.

[Cam Gould]

Probably related to #61