ec_donate.module.patch

gistfile1.txt

--- a/sites/all/modules/ec_donate/ec_donate.module
+++ b/sites/all/modules/ec_donate/ec_donate.module
@@ -520,10 +520,11 @@ function ec_donate_form_ec_checkout_product_form_alter(&$form, &$form_state) {
     }
     else {
       // ensure handler runs first
-      $form['submit']['cart']['#submit'] = array(
-        'ec_donate_user_entered_price_form_submit',
-        reset($form['submit']['cart']['#submit']),
-      );
+      if ( is_null($form['submit']['cart']['#submit']) ) {
+        $form['submit']['cart']['#submit'] = array( 'ec_donate_user_entered_price_form_submit' );
+      } else {
+        $form['submit']['cart']['#submit'] = array( 'ec_donate_user_entered_price_form_submit', reset($form['submit']['cart']['#submit']) );
+      }
     }
     // do we add a "Donate Now" button
     if ( isset($node->donate_now) && $node->donate_now) {