Fix issue where ONLY media in CKEditor would work

templates/content/media.html.twig

@@ -23,7 +23,9 @@
 
 {% set modifier_classes = '' %}
 
-{% set classes = classes | merge(attributes.class) %}
+{% if attributes.class %}
+ {% set classes = classes | merge(attributes.class) %}
+{% endif %}
 
 {% for class in classes %}
  {% set modifier_classes = modifier_classes ~ ' ' ~ class %}