--- betterselect.module (saved version)
+++ (current document)
@@ -224,6 +224,9 @@
  * Restore submitted checkbox values back to format Taxonomy module expects.
  */
 function betterselect_taxonomy_from_checkboxes($form, &$form_state) {
+  if (!is_array($form_state['values']['taxonomy'])) {
+    return;
+  }
   foreach ($form_state['values']['taxonomy'] as $index => $properties) {
     if (is_numeric($index) && $form['taxonomy'][$index]['#multiple']) {
       $options = array();