This fixes cases where the last step can't be reached because it's currently skipped, which should mark the end of the process instead of throwing a runtime exception: "Cannot determine next step."

Then $flow->isFinished() will return true, but you must call the handler of the clicked button manually before checking $flow->isFinished() so this escenario will be covered:

if ($flow->isSubmitted() && $flow->isValid()) {
    // ensure the flow button is handled before checking whether it's finished
    $flow->getClickedButton()->handle();

    if ($flow->isFinished()) {
        // do something with $form->getData()

        return $this->redirectToRoute('some_route');
    }
}

For other cases, you can continue using the simplified version of this controller.