internal events should not be in external calender

events.ics

@@ -29,7 +29,7 @@ END:VTIMEZONE
 PRODID:https://chaotikum.org/
 METHOD:PUBLISH
 {% for event in site.events %}
-{%- if e.nofrontpage == nil or e.nofrontpage == '' -%}
+{%- if event.nofrontpage == nil or event.nofrontpage == '' -%}
 BEGIN:VEVENT
 UID:{{ event.uid }}
 ORGANIZER;CN={% if event.organizer and event.organizer != "" and event.organizer != nil %}{{event.organizer}}{% else %}Chaotikum e.V.{% endif %}:MAILTO:{{event.contact}}