After autoprovisioning a user, we need to get a reva token via `auth-machine`. If that fails the code would panic because the logger tried to access the `user` object returned from the GetUserByClaims call. Which is `nil`in case failure. Fixes #936
After autoprovisioning a user, we need to get a reva token via `auth-machine`. If that fails the code would panic because the logger tried to access the `user` object returned from the GetUserByClaims call. Which is `nil`in case failure. Fixes #936