Limit issue in getting order

[creativegeniusod]

when I try to implement order api
$orders = $client->listAll([
'createdStartDate' => '2016-06-01', // optional
'limit' => '19',

]);

print_r($orders);

its showing error Fatal error: Call to a member function getStatusCode() on a non-object in /home/ubuntu/workspace/vendor/fillup/walmart-partner-api-sdk-php/src/Order.php on line 124

[creativegeniusod]

Please reply asap