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Fatal error: Uncaught TypeError: hash_equals(): Argument #1 ($known_string) must be of type string, null given in /home/users/bannerapp/www/classes/Sahu/Shopify/Auth.php:38 Stack trace: #0 /home/users/bannerapp/www/classes/Sahu/Shopify/Auth.php(38): hash_equals() #1 /home/users/bannerapp/www/check_token.php(12): Sahu\Shopify\Auth::isValidHMAC() #2 /home/users/bannerapp/www/index.php(3): require_once('...') #3 {main} thrown in /home/users/bannerapp/www/classes/Sahu/Shopify/Auth.php on line 38