Unable to perform update when adding new menu field

Question

I'm attempting to add a custom image field to my menu from a custom module like so

function my_module_entity_base_field_info(EntityTypeInterface $entity_type) {
  $fields = array();
      if ($entity_type->id() === 'menu_link_content') {
          $fields['menu_link_secondary_image'] = BaseFieldDefinition::create('image')
              ->setLabel(t('Menu link secondary image'))
              ->setDescription(t('Upload a secondary image related to this menu item'))
              ->setDisplayOptions('form',array('type' => 'image','weight' => 1))
              ->setDisplayConfigurable('form',TRUE)
          ->setSettings([
              'file_directory' => 'public://',
              'alt_field_required' => 'FALSE',
              'file_extensions' => 'png jpg jpeg',
          ]);

      return $fields;
    }
}

Then in my update function I have

function my_module_update_8001(){
    $entity_manager = \Drupal::entityManager();
    $definitions = $entity_manager->getLastInstallFieldStorageDefinitions('menu_link_content');
    if(!isset($definitions['menu_link_secondary_image']) || empty($definitions['menu_link_secondary_image'])){
        $definition = $entity_manager->getFieldStorageDefinitions('menu_link_content')['menu_link_secondary_image'];
        $entity_manager->onFieldStorageDefinitionCreate($definition);
    }
}

But when I attempt to run update.php it hangs and I get errors like

Notice: Undefined index: menu_link_secondary_image__alt in Drupal\Core\Entity\Sql\SqlContentEntityStorage->loadFromSharedTables()

Strangely enough I added a menu link afterwards and my field was actually there. I couldn't tell if my update actually worked and just didn't act as if it did, or if it already worked before hand and the update was unnecessary. Did I do something wrong?

UPDATE: I see that although my field appeared I'm unable to save it due to this error

Column not found: 1054 Unknown column 'menu_link_secondary_image__target_id' i

Answer 1

Just update entities it will work: run the command drush entity-updates.
No need for hook_update_N.
You can add hook_install to update entities automatically when you install your module don't need to do it by command each time or get the error on every installation .

/**
 * Implements hook_install().
 */
function my_module_install() {
  \Drupal::service('entity.definition_update_manager')->applyUpdates();
}