commit 3c0faea89b22977d29db31774fb7d6f259dce495
Author: Joel Pittet <joel@pittet.ca>
Date:   Mon Nov 18 20:36:35 2013 -0800

    remove debug and add isset()

diff --git a/core/themes/engines/twig/twig.engine b/core/themes/engines/twig/twig.engine
index cb5a54f..0e62158 100644
--- a/core/themes/engines/twig/twig.engine
+++ b/core/themes/engines/twig/twig.engine
@@ -141,8 +141,7 @@ function twig_hide($element) {
     if (count($args) > 1) {
       array_shift($args);
       foreach($args as $arg) {
-        debug($arg);
-        $element[$arg]['#printed'] = TRUE;
+        if (isset($element[$arg])) $element[$arg]['#printed'] = TRUE;
       }
     }
   }