PHP 对话流(无法构建 ApplicationDefaultCredentials)

(Could not construct ApplicationDefaultCredentials) for PHP dialogflow

use Google\Cloud\Storage\StorageClient;
use Google\Cloud\Dialogflow\V2\EntityTypesClient;

$storage = new StorageClient([
            'keyFile' => json_decode(file_get_contents(storage_path('app/public/tunepath-bot-tkpf-811257321355.json')), true)
        ]);

        $entityTypesClient = new EntityTypesClient();
        $projectId = '[project_id]';
        $entityTypeId = '[ENTITY_TYPE_ID]';
        $formattedEntityTypeName = $entityTypesClient->entityTypeName($projectId, $entityTypeId);

        $entityType = $entityTypesClient->getEntityType($formattedEntityTypeName);
        foreach ($entityType->getEntities() as $entity) {
            print(PHP_EOL);
            printf('Entity value: %s' . PHP_EOL, $entity->getValue());
            print('Synonyms: ');
            foreach ($entity->getSynonyms() as $synonym) {
                print($synonym . "\t");
            }
            print(PHP_EOL);
        }

我已经按照文档做了https://github.com/googleapis/google-cloud-php-dialogflow。我收到此错误 - 无法构造 ApplicationDefaultCredentials

putenv("GOOGLE_APPLICATION_CREDENTIALS=$path");

$path -> google 服务帐户 json 文件的路径。 把这段代码放在上面。