[TEST] make PHP 5.x happy

Author: polyfractal

src/Elasticsearch/Transport.php

@@ -113,9 +113,10 @@ function ($response) {
                 // Note, this could be a 4xx or 5xx error
             },
             //onFailure
-            function ($response) {
+            function (\Exception $response) {
                 // Ignore 400 level errors, as that means the server responded just fine
-                if (!(isset($response['code']) && $response['code'] >=400 && $response['code'] < 500)) {
+                $code = $response->getCode();
+                if (!(isset($code) && $code >=400 && $code < 500)) {
                     // Otherwise schedule a check
                     $this->connectionPool->scheduleCheck();
                 }