Remove unused item classes initialization

agaric/templates/field/field.html.twig

@@ -47,8 +47,6 @@
   ]
 %}
 {% set title_attributes = title_attributes.addClass(title_classes) %}
-{# Child templates can specify classes to be added to items. #}
-{% set item_classes = item_classes ?? [] %}
 
 {% if label_hidden %}
   {% for item in items %}