Warning: Undefined array key "HTTP_STRIPE_SIGNATURE" in /var/www/html/wp-content/themes/wpresidence/stripecharge.php on line 8

Fatal error: Uncaught Stripe\Exception\SignatureVerificationException: Unable to extract timestamp and signatures from header in /var/www/html/wp-content/plugins/wpresidence-core/resources/stripe-php-master/lib/Exception/SignatureVerificationException.php:28
Stack trace:
#0 /var/www/html/wp-content/plugins/wpresidence-core/resources/stripe-php-master/lib/WebhookSignature.php(31): Stripe\Exception\SignatureVerificationException::factory('Unable to extra...', '', '')
#1 /var/www/html/wp-content/plugins/wpresidence-core/resources/stripe-php-master/lib/Webhook.php(29): Stripe\WebhookSignature::verifyHeader('', '', '', 300)
#2 /var/www/html/wp-content/themes/wpresidence/stripecharge.php(18): Stripe\Webhook::constructEvent('', '', '')
#3 /var/www/html/wp-includes/template-loader.php(132): include('/var/www/html/w...')
#4 /var/www/html/wp-blog-header.php(19): require_once('/var/www/html/w...')
#5 /var/www/html/index.php(17): require('/var/www/html/w...')
#6 {main}
  thrown in /var/www/html/wp-content/plugins/wpresidence-core/resources/stripe-php-master/lib/Exception/SignatureVerificationException.php on line 28