Recent Fatal Error with Plugin

I had to disable the plugin recently because it was creating a critical error at checkout. The trace revealed the following:

Fatal error: Uncaught TypeError: Unsupported operand types: string – int in /home/288968.cloudwaysapps.com/qwvmhnscdx/public_html/wp-content/plugins/triplea-cryptocurrency-payment-gateway-for-woocommerce/includes/WooCommerce/TripleA_Payment_Gateway.php:692 Stack trace: #0 /home/288968.cloudwaysapps.com/qwvmhnscdx/public_html/wp-content/plugins/triplea-cryptocurrency-payment-gateway-for-woocommerce/includes/WooCommerce/TripleA_Payment_Gateway.php(81): Triplea\WcTripleaCryptoPayment\WooCommerce\TripleA_Payment_Gateway->refreshOauthTokens() #1 /home/288968.cloudwaysapps.com/qwvmhnscdx/public_html/wp-content/plugins/triplea-cryptocurrency-payment-gateway-for-woocommerce/triplea-cryptocurrency-payment-gateway-for-woocommerce.php(138): Triplea\WcTripleaCryptoPayment\WooCommerce\TripleA_Payment_Gateway->__construct() #2 /home/288968.cloudwaysapps.com/qwvmhnscdx/public_html/wp-includes/class-wp-hook.php(308): WC_Tripla_Crypto_Payment->triplea_wc_add_gateway_class() #3 /home/288968.cloudwaysapps.com/qwvmhnscdx/public_html/wp-includes/plugin.php(205): WP_Hook->apply_filters() #4 /home/288968.cloudwaysapps.com/qwvmhnscdx/public_html/wp-content/plugins/woocommerce/includes/class-wc-payment-gateways.php(88): apply_filters() #5 /home/288968.cloudwaysapps.com/qwvmhnscdx/public_html/wp-content/plugins/woocommerce/includes/class-wc-payment-gateways.php(70): WC_Payment_Gateways->init() #6 /home/288968.cloudwaysapps.com/qwvmhnscdx/public_html/wp-content/plugins/woocommerce/includes/class-wc-payment-gateways.php(43): WC_Payment_Gateways->__construct() #7 /home/288968.cloudwaysapps.com/qwvmhnscdx/public_html/wp-content/plugins/woocommerce/includes/class-woocommerce.php(961): WC_Payment_Gateways::instance() #8 /home/288968.cloudwaysapps.com/qwvmhnscdx/public_html/wp-content/plugins/woocommerce/includes/wc-template-functions.php(73): WooCommerce->payment_gateways() #9 /home/288968.cloudwaysapps.com/qwvmhnscdx/public_html/wp-includes/class-wp-hook.php(308): wc_template_redirect() #10 /home/288968.cloudwaysapps.com/qwvmhnscdx/public_html/wp-includes/class-wp-hook.php(332): WP_Hook->apply_filters() #11 /home/288968.cloudwaysapps.com/qwvmhnscdx/public_html/wp-includes/plugin.php(517): WP_Hook->do_action() #12 /home/288968.cloudwaysapps.com/qwvmhnscdx/public_html/wp-includes/template-loader.php(13): do_action() #13 /home/288968.cloudwaysapps.com/qwvmhnscdx/public_html/wp-blog-header.php(19): require_once(‘/home/288968.cl…’) #14 /home/288968.cloudwaysapps.com/qwvmhnscdx/public_html/index.php(17): require(‘/home/288968.cl…’) #15 {main} thrown in?/home/288968.cloudwaysapps.com/qwvmhnscdx/public_html/wp-content/plugins/triplea-cryptocurrency-payment-gateway-for-woocommerce/includes/WooCommerce/TripleA_Payment_Gateway.php?on line?692