Side cart not opening

Hello,

The Side cat is not opening and I am having an error when I installed your plugin.
Here is the message I get:

wp-content/plugins/woocommerce/includes/class-wc-cart.php:2032
WC_Cart->get_product_subtotal()
wp-content/plugins/woo-conditional-product-fees-for-checkout/woocommerce/checkout/review-order.php:42
wc_get_template()
wp-content/plugins/woocommerce/includes/wc-template-functions.php:2263
woocommerce_order_review()
wp-includes/class-wp-hook.php:287
do_action('vi_wcaio_checkout_order_review')
wp-content/plugins/woocommerce-cart-all-in-one/includes/frontend/form-checkout.php:27
VIWCAIO_CART_ALL_IN_ONE_Frontend_Form_Checkout::viwcaio_checkout_step_order_review()
wp-includes/class-wp-hook.php:287
do_action('vi_wcaio_checkout_step_order_review')
wp-content/plugins/woocommerce-cart-all-in-one/includes/templates/form-checkout.php:143
wc_get_template()
wp-content/plugins/woocommerce-cart-all-in-one/includes/frontend/sidebar-cart-content.php:605
VIWCAIO_CART_ALL_IN_ONE_Frontend_Sidebar_Cart_Content->get_sidebar_cart_content()
wp-includes/class-wp-hook.php:287
do_action('vi_wcaio_get_sidebar_cart_content')
wp-content/plugins/woocommerce-cart-all-in-one/includes/frontend/sidebar-cart-content.php:529
VIWCAIO_CART_ALL_IN_ONE_Frontend_Sidebar_Cart_Content->frontend_html()
wp-includes/class-wp-hook.php:287
do_action('wp_footer')
wp-includes/general-template.php:3021
wp_footer()
wp-content/themes/krowd/footer.php:60
load_template('wp-content/themes/krowd/footer.php')
wp-includes/template.php:676
locate_template()
wp-includes/general-template.php:92
get_footer()
wp-content/themes/krowd/page.php:22

Thanks in advance,
— GM