Help! Error: Notice: Undefined property: WooCommerce::$payment_gateways

Hi,
This error is showing up in the checkout page, Could you tell me why this is happening?

Notice: Undefined property: WooCommerce::$payment_gateways in /home/forge/omegaammo.com/wp-content/plugins/postcode-based-order-restriction/woocommerce-postcode-order-restriction.php on line 188

Notice: Trying to get property of non-object in /home/forge/omegaammo.com/wp-content/plugins/postcode-based-order-restriction/woocommerce-postcode-order-restriction.php on line 188

Thank you for the help!