Handle missing author url

Author: gidsi

templates/stuff.html

@@ -66,14 +66,14 @@ <h3>
   </h3>
   <p>
     This app was made by
-    <a href="{{ this.author_url }}">
+    {% if this.author_url %}<a href="{{ this.author_url }}">{% endif %}
       {{ this.author }}
-    </a>
+    {% if this.author_url %}</a>{% endif %}
     {% if this.author2 %}
       and
-      <a href="{{ this.author2_url }}">
-        {{ this.author2 }}
-      </a>
+      {% if this.author2_url %}<a href="{{ this.author2_url }}">{% endif %}
+          {{ this.author2 }}
+      {% if this.author2_url %}</a>{% endif %}
     {% endif %}
     from
     <a href="{{ this.space_url }}">