fix: fFatal error: Uncaught TypeError

related: quiqqer/payment-stripe#14

src/QUI/ERP/Payments/Stripe/AbstractBasePayment.php

@@ -103,7 +103,7 @@ public function isSuccessful(string $hash): bool
             return false;
         }
 
-        return $Order->getPaymentDataEntry(self::ATTR_STRIPE_ORDER_SUCCESSFUL);
+        return (bool)$Order->getPaymentDataEntry(self::ATTR_STRIPE_ORDER_SUCCESSFUL);
     }
 
     /**