Ensure I don't forget to write something in the description

It's easy to miss in reviews and when I am in the flow.

templates/partials/header.html

@@ -34,6 +34,11 @@
 
     {% set description = page.description | default(value=config.description) %}
     {% set description_length = description | length %}
+    {# Ensure I don't forget to write something in the description #}
+    {% if description_length == 0 %}
+        {{ throw(message="Description is empty") }}
+    {% endif %}
+
     {# The description must be at most 200 characters, more is not recommended. This is enforced below. #}
     {% if description_length > 200 %}
         {{ throw(message="Description is longer than 200 characters (" ~ description_length ~ "): " ~ description ) }}