_appendExternalTemplates(loadedElements) {
    if (!Array.isArray(loadedElements))
      loadedElements = [loadedElements];
    const head = document.getElementsByTagName("head")[0];
    let errors = 0;
    loadedElements.forEach((element) => {
      if (Array.isArray(element)) {
        console.error(...element);
        errors++;
      } else {
        head.append(element);
      }
    });
    return errors;
  }
Apply fetched external elements to templates tags under the head tag
@param {HTMLElement[]} loadedElements Array of loaded external elements to add as templates to the head tag
@returns {number} Count of load errors