Make config.description optional in atom.xml
<?xml version="1.0" encoding="UTF-8"?>
<feed xmlns="http://www.w3.org/2005/Atom" xml:lang="{{ config.default_language }}">
<title>{{ config.title }}</title>
+ {%- if config.description %}
<subtitle>{{ config.description }}</subtitle>
+ {%- endif %}
<link href="{{ feed_url | safe }}" rel="self" type="application/atom+xml"/>
<link href="{{ config.base_url | safe }}"/>
<generator uri="https://www.getzola.org/">Zola</generator>
