获取身份验证令牌时发生StreamLabs API'grant_type'错误

Question

我正尝试从StreamLabs API获取身份验证令牌，并且具有所有必需的参数，尽管出于某些原因，我仍然会收到以下正文响应：

{"error":"invalid_request","error_description":"The request is missing a required parameter, includes an invalid parameter value, includes a parameter more than once, or is otherwise malformed. Check the \"grant_type\" parameter."}

当我尝试运行此代码时：

var dataString = `grant_type=authorization_code
                    &client_id=123asd123asd
                    &client_secret=666777rrrtttawd123
                    &redirect_uri=https%3A%2F%2Fredirect.com%2Fauth
                    &code=${req.query.code}`;
  var options = {
      url: 'https://streamlabs.com/api/v1.0/token',
      method: 'POST',
      body: dataString
  };
  function callback(error, response, body) { console.log(body); }
  request(options, callback);

grant_type参数正确