Get the error from the child process in the correct way

Author: WyriHaximus

src/ChildProcess/Adapter.php

@@ -130,8 +130,8 @@ public function callFilesystem($function, $args, $errorResultCode = -1)
     {
         return $this->pool->rpc(Factory::rpc($function, $args))->then(function (Payload $payload) {
             return \React\Promise\resolve($payload->getPayload());
-        }, function (Payload $payload) {
-            return \React\Promise\reject(new Exception($payload->getPayload()['error']['error']['message']));
+        }, function ($payload) {
+            return \React\Promise\reject(new Exception($payload['error']['message']));
         });
     }