diff --git a/core/themes/classy/templates/form/details.html.twig b/core/themes/classy/templates/form/details.html.twig
index 9b149d7..46d8dd0 100644
--- a/core/themes/classy/templates/form/details.html.twig
+++ b/core/themes/classy/templates/form/details.html.twig
@@ -5,6 +5,7 @@
*
* Available variables
* - attributes: A list of HTML attributes for the details element.
+ * - errors: (optional) Any errors for this details element, may not be set.
* - title: (optional) The title of the element, may not be set.
* - description: (optional) The description of the element, may not be set.
* - children: (optional) The children of the element, may not be set.
@@ -18,6 +19,11 @@