Fixed bug in pub search

tripal_pub/includes/tripal_pub.pub_search.inc

@@ -142,7 +142,7 @@ function tripal_pub_search_form($form, &$form_state) {
 
   // if the session has variables then use those.  This should only happen when
   // the 'Test Criteria' button is clicked.
-  if ($_SESSION and array_key_exists('tripal_pub_search_form', $_SESSION)) {
+  if (defined($_SESSION) and array_key_exists('tripal_pub_search_form', $_SESSION)) {
     $num_criteria = $_SESSION['tripal_pub_search_form']['num_criteria'] ? $_SESSION['tripal_pub_search_form']['num_criteria'] : $num_criteria;
     $from_year    = $_SESSION['tripal_pub_search_form']['from_year']    ? $_SESSION['tripal_pub_search_form']['from_year']    : '';
     $to_year      = $_SESSION['tripal_pub_search_form']['to_year']      ? $_SESSION['tripal_pub_search_form']['to_year']      : '';