Authorizenet: Undefined property error and temporary fix

Sites using Authorize net for payments are receiving error on payment section of checkout:  Warning: Undefined property: os_authnet::$showCardType in /home/stringtr/public_html/administrator/components/com_eshop/libraries/erad/payment/tmpl/form.php on line 72

Temporary fix: Go to:file:/administrator/components/com_eshop/libraries/erad/payment/tmpl/form.php.
Locate line 72.
Replace: if ($this->showCardType) {
  with this:
if (isset($this->showCardType) && $this->showCardType) {