Compatibility with form_mode_manager module

Seems this is not going to get fixed, so I will close this issue.

Fro anyone else that wants this, I'm currently using this fix in custom code.

/**
 * Implements hook_form_alter().
 */
function my_module_form_alter(&$form, \Drupal\Core\Form\FormStateInterface $form_state, $form_id) {
  $form_mode_manager_exists = Drupal::moduleHandler()->moduleExists('form_mode_manager');
  if ($form_mode_manager_exists && function_exists('roleassign_form_alter')) {
    /** @var \Drupal\form_mode_manager\FormModeManager $form_mode_manager */
    $form_mode_manager = \Drupal::service('form_mode.manager');
    $form_modes = $form_mode_manager->getFormModesByEntity('user');
    foreach ($form_modes as $name => $form_mode) {
      if ($form_id === 'user_' . $name . '_form') {
        roleassign_form_alter($form, $form_state, 'user_form');
      }
    }
  }
}