How to show contextual links / quick edit links for blocks

Question

I'm building a Drupal 8 template/theme from scratch, and it is not showing the contextual editing options for my blocks when I view a site page. I.E., the little circles that are clicked to see options like "edit view," "configure block," etc.

I cloned the block.html.twig from the Bartik theme, so it has the attributes token that I thought was enough, like this:

<div{{ attributes.addClass(classes) }}>
 {{ title_prefix }}
 {% if label %}
   <h2{{ title_attributes }}>{{ label }}</h2>
 {% endif %}
 {{ title_suffix }}
 {% block content %}
   <div{{ content_attributes.addClass('content') }}>
     {{ content }}
   </div>
 {% endblock %}
 </div>

I can confirm the Contextual links module is active.

I have global access, so it shouldn't be a permissions issue.

Is there something more I need to do for this feature to be added in?

Answer 1

Per 'No Sssweat's comment above, this was due to a small syntax error in a custom javascript file, viewable in console. Once corrected, the contextual links worked as intended.