Critical Error on User Registration

I got this error after update. Please check it sir. Thanks!

Notice: Undefined index: Woo_Wallet_Email_New_Transaction in /home/bluebellhalal/public_html/wp-content/plugins/woo-wallet/includes/class-woo-wallet-wallet.php on line 215

Fatal error: Uncaught Error: Call to a member function trigger() on null in /home/bluebellhalal/public_html/wp-content/plugins/woo-wallet/includes/class-woo-wallet-wallet.php:216 Stack trace: #0 /home/bluebellhalal/public_html/wp-content/plugins/woo-wallet/includes/class-woo-wallet-wallet.php(74): Woo_Wallet_Wallet->recode_transaction(’10’, ‘credit’, ‘Free RM10 for n…’) #1 /home/bluebellhalal/public_html/wp-content/plugins/woo-wallet/includes/actions/class-woo-wallet-action-new-registration.php(51): Woo_Wallet_Wallet->credit(351, ’10’, ‘Free RM10 for n…’) #2 /home/bluebellhalal/public_html/wp-includes/class-wp-hook.php(288): Action_New_Registration->woo_wallet_new_user_registration_credit(351) #3 /home/bluebellhalal/public_html/wp-includes/class-wp-hook.php(312): WP_Hook->apply_filters(NULL, Array) #4 /home/bluebellhalal/public_html/wp-includes/plugin.php(478): WP_Hook->do_action(Array) #5 /home/bluebellhalal/public_html/wp-includes/user.php(1897): do_action(‘user_register’, 351) #6 /home/bluebellhalal/public_html/wp- in /home/bluebellhalal/public_html/wp-content/plugins/woo-wallet/includes/class-woo-wallet-wallet.php on line 216

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