阿里云人脸实名认证代码报错：Credential 'default' not found

阿里云人脸实名认证代码报错：Credential 'default' not found

这个怎么解决？

<?php
namespace AlibabaCloud\SDK\Sample {
  
use AlibabaCloud\Credentials\Credential;
use AlibabaCloud\SDK\Cloudauth\V20200618\Cloudauth;
use AlibabaCloud\Tea\Utils\Utils;
use AlibabaCloud\Tea\Exception\TeaError;
use \Exception;
use AlibabaCloud\Tea\Rpc\Rpc\Config;
use AlibabaCloud\SDK\Cloudauth\V20200618\Models\InitSmartVerifyRequest;
use AlibabaCloud\SDK\Cloudauth\V20200618\Models\InitSmartVerifyResponse;
use AlibabaCloud\Tea\Utils\Utils\RuntimeOptions;

class InitSmartVerify {

    /**
     * @param string $endpoint
     * @return Cloudauth
     */
    public static function createClient($endpoint){
        // 阿里云账号AccessKey拥有所有API的访问权限，建议您使用RAM用户进行API访问或日常运维。
        // 强烈建议不要把AccessKey ID和AccessKey Secret保存到工程代码里，否则可能导致AccessKey泄露，威胁您账号下所有资源的安全。
        // 本示例通过阿里云Credentials工具从环境变量中读取AccessKey，来实现API访问的身份验证。如何配置环境变量，请参见 https://help.aliyun.com/document_detail/311677.html。 
        $credential = new Credential([]);
        $config = new Config([
	        // 使用credential配置凭证
    		    "credential" => $credential,
            // 设置HTTP代理。
            // "httpProxy" => "<http://xx.xx.xx.xx:xxxx>",
            // 设置HTTPS代理
            // "httpsProxy" => "<https://xx.xx.xx.xx:xxxx>",
            "endpoint" => $endpoint

        ]);
        return new Cloudauth($config);
    }

    /**
     * @return void
     */
    public static function main(){
        $request = new InitSmartVerifyRequest([
            // 请输入场景ID。
            "sceneId" => xxx,
            "outerOrderNo" => "<商户请求的唯一标识>",
            // 证件类型，固定值。
            "mode" => "MARKET_SAFE",
            "ocr" => "T",
            "certType" => "IDENTITY_CARD",
            // "certName" => "<张三>",
            // "certNo" => "<xxxxx>",
            // MetaInfo环境参数，需要通过客户端SDK获取。
            "metaInfo" => '{"zimVer":"3.0.0","appVersion": "1","bioMetaInfo": "4.1.0:11501568,0",
        "appName": "com.aliyun.cloudauth","deviceType": "ios","osVersion": "iOS 10.3.2","apdidToken": "","deviceModel": "iPhone9,1"}',
            "mobile" => "<130xxxxxxxx>",
            // "ip" => "<114.xxx.xxx.xxx>",
            // "userId" => "<12345xxxx>",
            // "callbackUrl" => "<https://www.aliyundoc.com>",
            // "callbackToken" => "<xxxxxxx>"
        ]);
        // 推荐，支持服务自动路由。
        $response = self::initSmartVerifyAutoRoute($request);
        // 不支持服务自动路由。
        // $response = self::initSmartVerify("cloudauth.cn-shanghai.aliyuncs.com", $request);
        var_dump($response->requestId);
        var_dump($response->code);
        var_dump($response->message);
        var_dump($response->resultObject->certifyId);
    }

    /**
     * @param InitSmartVerifyRequest $request
     * @return InitSmartVerifyResponse
     */
    public static function initSmartVerifyAutoRoute(InitSmartVerifyRequest $request){
        $endpoints = [
            "cloudauth.cn-shanghai.aliyuncs.com",
            "cloudauth.cn-beijing.aliyuncs.com"
        ];
        foreach($endpoints as $endpoint){
            try {
                $response = self::initSmartVerify($endpoint, $request);
                if (Utils::equalString("500", $response->code)) {
                    continue;
                }
                return $response;
            }
            catch (Exception $err) {
                if (!($err instanceof TeaError)) {
                    $err = new TeaError([], $err->getMessage(), $err->getCode(), $err);
                }
                // 网络异常，切换到下个区域调用。
                if (Utils::equalString("ServiceUnavailable", $err->code)) {
                    continue;
                }
            }
        }
        return null;
    }

    /**
     * @param string $endpoint
     * @param InitSmartVerifyRequest $request
     * @return InitSmartVerifyResponse
     */
    public static function initSmartVerify($endpoint, $request){
        $client = self::createClient($endpoint);
        // 创建RuntimeObject实例并设置运行参数。
        $runtime = new RuntimeOptions([]);
        $runtime->readTimeout = 10000;
        $runtime->connectTimeout = 10000;
        return $client->initSmartVerify($request, $runtime);
    }
}
$path = __DIR__ . \DIRECTORY_SEPARATOR . \DIRECTORY_SEPARATOR . 'vendor' . \DIRECTORY_SEPARATOR . 'autoload.php';
if (file_exists($path)) {
    require_once $path;
}
InitSmartVerify::main();
}