_createUser() async {
UserUpdateInfo updateInfo = UserUpdateInfo();
updateInfo.displayName = _usernameController.text;

FirebaseUser user = await _auth
    .createUserWithEmailAndPassword(
  email: _emailController.text,
  password: _passwordController.text,
)
    .then((user) {
  user.updateProfile(updateInfo);
});
print('USERNAME IS: ${user.displayName}');
}

NoSuchMethodError: The getter 'displayName' was called on null.