mangopay intergation in node js. Could not create user

I am integrating mangopay in node js and I am using npm for mangopay2-nodejs-sdk.but when I use api.Users.create function for creating user ,it gives me error

Debug: internal, implementation, error TypeError: Uncaught error: Cannot read property 'userClass' of undefined at Service.extend.create (/home/hashir/artpaie/artapieapp/artapieBackend/node_modules/mangopay2-nodejs-sdk/lib/services/Users.js:38:41)

via asfia siddiqui