Fixing error when running yarn start in pattern lab

templates/form/form-element.html.twig

@@ -44,4 +44,24 @@
  * @see template_preprocess_form_element()
  */
 #}
+{%
+  set classes = [
+    'js-form-item',
+    'form-item',
+    'js-form-type-' ~ type|clean_class,
+    'form-item-' ~ name|clean_class,
+    'js-form-item-' ~ name|clean_class,
+    title_display not in ['after', 'before'] ? 'form-no-label',
+    disabled == 'disabled' ? 'form-disabled',
+    errors ? 'form-item--error',
+  ]
+%}
+
+{%
+  set description_classes = [
+    'description',
+    description_display == 'invisible' ? 'visually-hidden',
+  ]
+%}
+
 {% include "@atoms/05-forms/_form-element.twig" %}