How to use <Show> in ssr?

export default function Home() {
  const [error, setShowError] = createSignal(false);
  const [_, { Form }] = createRouteAction(async (formData: FormData) => {
    const username = formData.get('username');

    if (username !== 'admin') {
      setShowError(true);
    }
  });

  return (
    <div>
      <Form>
        <label>Username</label>
        <input type="text" name="username" />
      </Form>

      <Show when={error()} keyed>
        oops, you failed
      </Show>
    </div>
  );
}