www: Prevent crash if no builds are present

Change-Id: Ia9be2a5e31fd33f77fb8dda6f541f23ba5a6b580
diff --git a/templates/wiki/device.html.twig b/templates/wiki/device.html.twig
index aa09626..33c82e0 100644
--- a/templates/wiki/device.html.twig
+++ b/templates/wiki/device.html.twig
@@ -25,6 +25,7 @@
           <hr />
           <div class="latest-builds">
             {% for build in downloads.latestBuilds %}
+              {% if build %}
               <div class="build-card">
                 <div class="title">{{ build.flavor|capitalize }}</div>
                 <div class="build-info">
@@ -58,6 +59,7 @@
                   </table>
                 </div>
               </div>
+              {% endif %}
             {% endfor %}
           </div>
         </div>