ToDo Doc Issue at https://docs.amplify.aws/react/start/getting-started/auth/#create-login-ui

[shanecp]

Describe the content issue:
The example ToDo app fails to compile.

The section,

return (
  <div style={styles.container}>
    <Heading level={1}>Hello {user.username}</Heading>
    <Button onClick={signOut}>Sign out</Button>
    <h2>Amplify Todos</h2>
    ...
  </div>
);

Nullable type user.username should be fixed as user?.username

URL page where content issue is:
https://docs.amplify.aws/react/start/getting-started/auth/#create-login-ui