fix bug

src/Shopify/lib/Graphql.php

@@ -26,7 +26,7 @@ class Graphql extends AbstractShopify
     {
         if (!$url) $url = $this->generateUrl();
         $response = HttpRequestGraphQL::post($url, $graphQL, $this->httpHeaders, $variables);
-        return $this->processResponseOld($response);
+        return $this->processResponse($response);
     }
 
     public function get($urlParams = array(), $url = null, $dataKey = null)