Block definitions should be at the top level, not the included level

templates/forms/inputs/role-slug.html.twig

@@ -1,9 +1,7 @@
-{% block input_role_slug %}
 {% include "forms/inputs/abstract/slug.html.twig" with
     {
         "type" : "role",
         "current_value" : role.slug,
         "col_width" : col_width
     }
-%}
-{% endblock %}
+%}