Can't resume login in a chrome extension

[mrpspring]

When I try to run resumeLogin in my background.js on a chrome extension I get the error: ?d41d:51 Uncaught (in promise) TypeError: asteroid.resumeLogin is not a function

The code that I am using is:

  const Asteroid = createClass();
  const asteroid = new Asteroid({
    endpoint: 'ws://localhost:3000/websocket'
  });
  asteroid.resumeLogin().then(userId => {
    console.log(userId);
  });

Any suggestions on how to do this?