Fatel error on Version 2.6.8

the last update of Version 2.6.8 broken my website. am checking php errors file showing following
There has been a critical error on this website

Fatal error: Uncaught TypeError: Argument 1 passed to Automattic\WooCommerce\Internal\Utilities\HtmlSanitizer::sanitize() must be of the type string, null given, called in /home/u705666514/domains/aptsomart.com/public_html/wp-content/plugins/woocommerce/includes/abstracts/abstract-wc-payment-gateway.php on line 308 and defined in /home/u705666514/domains/aptsomart.com/public_html/wp-content/plugins/woocommerce/src/Internal/Utilities/HtmlSanitizer.php:51
Stack trace:
#0 /home/u705666514/domains/aptsomart.com/public_html/wp-content/plugins/woocommerce/includes/abstracts/abstract-wc-payment-gateway.php(308): Automattic\WooCommerce\Internal\Utilities\HtmlSanitizer->sanitize(NULL, Array)
#1 /home/u705666514/domains/aptsomart.com/public_html/wp-content/plugins/woo-wallet/includes/class-woo-wallet-settings.php(313): WC_Payment_Gateway->get_title()
#2 /home/u705666514/domains/aptsomart.com/public_html/wp-content/plugins/woo-wallet/includes/class-woo-wallet-settings.php(169): Woo_Wallet_Settings->get_wc_payment_allowed_gateways()
in /home/u705666514/domains/aptsomart.com/public_html/wp-content/plugins/woocommerce/src/Internal/Utilities/HtmlSanitizer.php on line 51

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