Call to a member function isTranslatable() on null in _menu_ui_node_save()

Problem/Motivation

Deleting a node programmatically through $node->delete(), the error below occurs

Error: Call to a member function isTranslatable() on null in _menu_ui_node_save() (line 95 of core/modules/menu_ui/menu_ui.module).

Steps to reproduce

Adding a new moderation state "delete" into Editorial workflow after the node was archived, the admin user tries to cleanly delete the node.

function custom_module_form_page_submit (array $form, \Drupal\Core\Form\FormStateInterface $form_state){
  $entity = $form_state->getFormObject()->getEntity();
  $nid = $entity->id();
  if ($moderation_state == 'delete') {
    $nid = $entity->id();
    $node = Node::load($nid);
    if (isset($node)) {
     $node->delete();
    }
  }
}

After the user clicks "submit" button, the error occurs
The website encountered an unexpected error. Please try again later.
Error: Call to a member function isTranslatable() on null in _menu_ui_node_save() (line 95 of core/modules/menu_ui/menu_ui.module).

Proposed resolution

Remaining tasks

Adding the check condition ( if (isset($entity)) ) before accessing $entity->isTranslatable()

 
function _menu_ui_node_save(NodeInterface $node, array $values) {
  /** @var \Drupal\menu_link_content\MenuLinkContentInterface $entity */
  if (!empty($values['entity_id'])) {
    $entity = MenuLinkContent::load($values['entity_id']);
    if (isset($entity)) {
      if ($entity->isTranslatable()) {
       ......
    }
  }
  else {
    // Create a new menu_link_content entity.
    $entity = MenuLinkContent::create([
      'link' => ['uri' => 'entity:node/' . $node->id()],
      'langcode' => $node->language()->getId(),
    ]);
    $entity->enabled->value = 1;
  }
  if (isset($entity)) {
     .......
    $entity->save();
  }
}

User interface changes

API changes

Data model changes

Release notes snippet