ISTWCMS-4199: updating node template so that it stops throwing errors on compile

source/_patterns/03-layouts/node/node.twig

+{% if classes %}
+  {% set classes = classes %}
+{% else %}
+  {% set classes = [] %}
+{% endif %}
+
 {% if has_sidebar == 'Yes' %}
   {% set classes = classes | merge(['uw-node__node--with-sidebar']) %}
 {% else %}