Fix exclude menu rendering bug

templates/_macros.html

@@ -9,7 +9,8 @@
 
 <nav>
     {% for page in section.pages %}
-    {% if config.extra.juice_exclude_menu and config.extra.juice_exclude_menu is not containing(page.title) %}
+    {% set exclude_menu = config.extra.juice_exclude_menu | default(value=[]) %}
+    {% if exclude_menu is not containing(page.title) %}
     <a class="nav-item subtitle-text" href="{{ page.permalink | safe }}">{{ page.title }}</a>
     {% endif %}
     {% endfor %}