Trying to get property of non-object

[fixern256]

Have this code that generates a error Trying to get property of non-object, that I cant figure out

    $order = $this->_createOrder($details['clientid']);
                $arr = json_decode($order); 
                $details['order'] = $order;
                $details['addorderresult'] = $arr->result;
 
            }

[Dormilich]

which of those lines generates the error?

[fixern256]

$order = $this->_createOrder($details['clientid']);
$arr = json_decode($order. true); 
$details['order'] = $order;
$details['addorderresult'] = (object)$arr['result'];
 

The two last ones but I changed it to following and now it seems to work.