Fixed error on main page.

templates/changelog/macros.twig

@@ -25,7 +25,7 @@
 {% endmacro %}
 
 {% macro changelog_entry(change, is_small, is_manage) %}
-    {% set user = change.user %}
+    {% set user = change.user|default(null) %}
     {% if change.change is defined %}
         {% set change = change.change %}
     {% endif %}