add date defaults

Author: staeiou

_includes/archive-single.html

@@ -39,9 +39,9 @@ <h2 class="archive__item-title" itemprop="headline">
     {% endif %}
 
     {% if post.venue and post.date %}
-      <p>Published in <i>{{ post.venue }}</i>, {{ post.date | date: "%Y" }} </p>
+      <p>Published in <i>{{ post.venue }}</i>, {{ post.date | default: "1900-01-01" | date: "%Y" }} </p>
     {% elsif post.date %}
-      <p class="page__date"><strong><i class="fa fa-fw fa-calendar" aria-hidden="true"></i> {{ site.data.ui-text[site.locale].date_label | default: "Published:" }}</strong> <time datetime="{{ page.date | date_to_xmlschema }}">{{ page.date | date: "%B %d, %Y" }}</time></p>
+      <p class="page__date"><strong><i class="fa fa-fw fa-calendar" aria-hidden="true"></i> {{ site.data.ui-text[site.locale].date_label | default: "Published:" }}</strong> <time datetime="{{ page.date | date_to_xmlschema }}">{{ page.date | default: "1900-01-01" | date: "%B %d, %Y" }}</time></p>
     {% endif %}
 
     {% if post.excerpt %}