getstream.io - Cannot create user in PHP backend

问题

I have created a React Native app with a stream from react-native-activity-feed. I use PHP as backend to generate the user session token;

$userId = "42";    
$userToken = client->createUserSessionToken($userId);

In my emulator I get following error:

TypeError: user_id is missing in user token.

This may be because I don't have any users yet on my app. When I try adding a user in my PHP backend using following code I get following error

$user = $client->users()->add('42', array('name' => 'Arthur Dent'));

Uncaught GuzzleHttp\Exception\ServerException: Server error: POST https://api.stream-io-api.com/api/v1.0/user/ resulted in a 502 Bad Gateway

How do I create a user?

来源：https://stackoverflow.com/questions/58488889/getstream-io-cannot-create-user-in-php-backend