JS doesn't render and breaks Elementor, editor screen just shows white or logo

[codewizard13]

This is a great tutorial -- even being 4 years old -- until (19:28) the part about JavaScript. The instructions you provided don't seem to work anymore right there.

https://youtu.be/Ko9i153o_iU?si=jYroVBecoB1frCcz&t=1168

These are some things I noticed according to the official Elementor Developer docs:

advertisment.php:

• _content_tempate(): has been renamed to remove the underscore prefix so now it is content_template()
• This bit starting at line 99 breaks the backend editor -- it tries to load but gets stuck:

<#
  view.addInlineEditingAttributes( 'label_heading', 'basic' );
  view.addRenderAttribute(
     'label_heading',
     {
         'class': [ 'advertisement__label-heading' ],
     }
   );
#>

• Replacing the preceding code with <h3>{{{ settings.label_heading }}}</h3> sort of works:

  protected function _content_template() {
  
  ?>
  
  <h3>{{{ settings.label_heading }}}</h3>

  <?php

  }

• Even weirder, even with only label_heading being called in content_template(), the back end shows the same as the front end (render()):

  // Front end
  protected function render() {

    $settings = $this->get_settings_for_display();
    $this->add_inline_editing_attributes('label_heading', 'basic');
    $this->add_render_attribute(
      'label_heading',
      [
        'class' => ['advertisement__label-heading'],
      ]
    );

    ?>

    <div class="advertisement">
      <div <?php echo $this->get_render_attribute_string('label_heading') ?> >
        <?php echo $settings['label_heading']; ?>
      </div>

      <div class="advertisement__content">
        <div class="advertisement__content__heading">
          <?php echo $settings['content_heading']; ?>
        </div>
        <div class="advertisement__content__copy">
          <?php echo $settings['content']; ?>
        </div>
      </div>
    </div>


    <?php

  }

  // Back end
  protected function content_template() {
  
  ?>
  
  <h3>{{{ settings.label_heading }}}</h3>

  <?php

  }

• I cleared cache - no change
• Regenerated Elementor files and data - no change
• Tried adding the underscore back to content_template() - no change

Why doesn't the JS render any different than the PHP when they should be showing different things (at this point, during testing the tutorial)?