Fix for !sn log msg: 'Undefined offset: 2 (./lib/activityobject.php:765)'

*vc-diff*.diff

diff --git a/lib/activityobject.php b/lib/activityobject.php
index 741aefd..3efb36c 100644
--- a/lib/activityobject.php
+++ b/lib/activityobject.php
@@ -633,7 +633,7 @@ class ActivityObject
             if ($source->created) {
                 $object->date = $source->created;
             }

             $object->extra[] = array('status_net', array('source_code' => $source->code));
 
             Event::handle('EndActivityObjectFromNoticeSource', array($source, &$object));
@@ -660,7 +660,7 @@ class ActivityObject
             }
 
             $object->extra[] = array('status_net', array('message_id' => $message->id));

             Event::handle('EndActivityObjectFromMessage', array($message, &$object));
         }
 
@@ -762,7 +762,7 @@ class ActivityObject
             // @fixme there's no way here to make a tree; elements can only contain plaintext
             // @fixme these may collide with JSON extensions
             foreach ($this->extra as $el) {
-                list($extraTag, $attrs, $content) = $el;
+	         list($extraTag, $attrs, $content) = array_pad($el,3,'');
                 $xo->element($extraTag, $attrs, $content);
             }