Alibaba Cloud SDK:Handle an exception

<?php

require_once 'vendor/autoload.php';
use AlibabaCloud\SDK\Ecs\V20140526\Ecs;
use AlibabaCloud\Tea\Utils\Utils\RuntimeOptions;
use Darabonba\OpenApi\Models\Config;
use AlibabaCloud\SDK\Ecs\V20140526\Models\DescribeInstancesRequest;
use AlibabaCloud\Tea\Exception\TeaError;
use AlibabaCloud\Tea\Exception\TeaUnableRetryError;

class ProxyDemo
{

    public static function main()
    {
        try {
            $config = new Config([
                "accessKeyId" => getenv("ALIBABA_CLOUD_ACCESS_KEY_ID"),
                "accessKeySecret" => getenv("ALIBABA_CLOUD_ACCESS_KEY_SECRET"),
                "endpoint" => "ecs.cn-beijing.aliyuncs.com", // <endpoint>
            ]);
            $client = new Ecs($config);

            $runtime = new RuntimeOptions([]);
            $describeInstancesRequest = new DescribeInstancesRequest([
                "regionId" => "cn-beijing"
            ]);
            $resp = $client->describeInstancesWithOptions($describeInstancesRequest, $runtime);
            var_dump($resp);
        } catch (\Exception $error) {
            if ($error instanceof TeaError) {
                // Handle exceptions with caution in your actual business scenario and do not ignore exceptions in your project. In this example, error messages are printed for reference only. 
                print_r("message:" . $error->getMessage() . "\n");
                print_r("code:" . $error->getCode() . "\n");
                print_r($error->data);
            } elseif ($error instanceof TeaUnableRetryError) {
                // Handle exceptions with caution in your actual business scenario and do not ignore exceptions in your project. In this example, error messages are printed for reference only. 
                print_r($error->getLastException());
            } else {
                // Handle exceptions with caution in your actual business scenario and do not ignore exceptions in your project. In this example, error messages are printed for reference only. 
                print_r("message:" . $error->getMessage());
            }
        }
    }
}
ProxyDemo::main();