message: Redirect to the registration page if there's a 3PID invite
  Fixes
diff: @@ -413,9 +413,13 @@ export default class MatrixChat extends React.PureComponent<IProps, IState> {
  });
  }).then((loadedSession) => {
  if (!loadedSession) {
  - // fall back to showing the welcome screen
  + // fall back to showing the welcome screen... unless we have a 3pid invite pending
  + if (ThreepidInviteStore.instance.pickBestInvite()) {
  + dis.dispatch({action: 'start_registration'});
  + } else {
  dis.dispatch({action: "view_welcome_page"});
  }
  + }
  });
  // Note we don't catch errors from this: we catch everything within
  // loadSession as there's logic there to ask the user if they want
  