Fatal Error on the checkout page.

[apeksha10]

Describe the bug
Fatal Error on the checkout page.

To Reproduce
Steps to reproduce the behavior:

1. PHP 8.0 setup
2. Try to place an order
3. On the checkout page, I got this error.

[17-Jan-2023 07:37:18 UTC] PHP Fatal error: Uncaught TypeError: Unsupported operand types: string - string in C:\Users\User\Local Sites\hpos\app\public\wp-content\plugins\checkout-fees-for-woocommerce\includes\class-alg-wc-checkout-fees.php:533
Stack trace:
#0 C:\Users\User\Local Sites\hpos\app\public\wp-content\plugins\checkout-fees-for-woocommerce\includes\class-alg-wc-checkout-fees.php(885): Alg_WC_Checkout_Fees->calculate_the_fee(Array, 0, 1101.8, 'fee_1')
#1 C:\Users\User\Local Sites\hpos\app\public\wp-content\plugins\checkout-fees-for-woocommerce\includes\class-alg-wc-checkout-fees.php(948): Alg_WC_Checkout_Fees->get_the_fee(Array, 'fee_both')
#2 C:\Users\User\Local Sites\hpos\app\public\wp-content\plugins\checkout-fees-for-woocommerce\includes\class-alg-wc-checkout-fees.php(416): Alg_WC_Checkout_Fees->maybe_add_cart_fee(Array)
#3 C:\Users\User\Local Sites\hpos\app\public\wp-includes\class-wp-hook.php(308): Alg_WC_Checkout_Fees->add_gateways_fees(Object(WC_Cart))
#4 C:\Users\User\Local Sites\hpos\app\public\wp-includes\class-wp-hook.php(332): WP_Hook->apply_filters('', Array)
#5 C:\Users\User\Local Sites\hpos\app\public\wp-includes\plugin.php(517): WP_Hook->do_action(Array)
#6 C:\Users\User\Local Sites\hpos\app\public\wp-content\plugins\woocommerce\includes\class-wc-cart.php(1888): do_action('woocommerce_car...', Object(WC_Cart))
#7 C:\Users\User\Local Sites\hpos\app\public\wp-content\plugins\woocommerce\includes\class-wc-cart-totals.php(272): WC_Cart->calculate_fees()
#8 C:\Users\User\Local Sites\hpos\app\public\wp-content\plugins\woocommerce\includes\class-wc-cart-totals.php(833): WC_Cart_Totals->get_fees_from_cart()
#9 C:\Users\User\Local Sites\hpos\app\public\wp-content\plugins\woocommerce\includes\class-wc-cart-totals.php(145): WC_Cart_Totals->calculate_fee_totals()
#10 C:\Users\User\Local Sites\hpos\app\public\wp-content\plugins\woocommerce\includes\class-wc-cart-totals.php(134): WC_Cart_Totals->calculate()
#11 C:\Users\User\Local Sites\hpos\app\public\wp-content\plugins\woocommerce\includes\class-wc-cart.php(1401): WC_Cart_Totals->_construct(Object(WC_Cart))
#12 C:\Users\User\Local Sites\hpos\app\public\wp-content\plugins\woocommerce\includes\class-wc-ajax.php(374): WC_Cart->calculate_totals()
#13 C:\Users\User\Local Sites\hpos\app\public\wp-includes\class-wp-hook.php(308): WC_AJAX::update_order_review('')
#14 C:\Users\User\Local Sites\hpos\app\public\wp-includes\class-wp-hook.php(332): WP_Hook->apply_filters(NULL, Array)
#15 C:\Users\User\Local Sites\hpos\app\public\wp-includes\plugin.php(517): WP_Hook->do_action(Array)
#16 C:\Users\User\Local Sites\hpos\app\public\wp-content\plugins\woocommerce\includes\class-wc-ajax.php(94): do_action('wc_ajax_update...')
#17 C:\Users\User\Local Sites\hpos\app\public\wp-includes\class-wp-hook.php(308): WC_AJAX::do_wc_ajax('')
#18 C:\Users\User\Local Sites\hpos\app\public\wp-includes\class-wp-hook.php(332): WP_Hook->apply_filters(false, Array)
#19 C:\Users\User\Local Sites\hpos\app\public\wp-includes\plugin.php(517): WP_Hook->do_action(Array)
#20 C:\Users\User\Local Sites\hpos\app\public\wp-includes\template-loader.php(13): do_action('template_redire...')
#21 C:\Users\User\Local Sites\hpos\app\public\wp-blog-header.php(19): require_once('C:\Users\User\L...')
#22 C:\Users\User\Local Sites\hpos\app\public\index.php(17): require('C:\Users\User\L...')
#23 {main}
thrown in C:\Users\User\Local Sites\hpos\app\public\wp-content\plugins\checkout-fees-for-woocommerce\includes\class-alg-wc-checkout-fees.php on line 533

https://www.screencast.com/t/v1TNg3HYuT

Setting screenshots: https://www.screencast.com/t/EfyPnJBl
https://www.screencast.com/t/pfL7Pw9JdF
https://www.screencast.com/t/VZZnG18cve
https://www.screencast.com/t/ad0oZRctJz

Expected behavior
No error must be thrown from our plugin.