Loading non-existent entity returns NULL

In Drupal 7 *_load() functions (node_load(), comment_load(), etc.) derived from entity_load() and also the menu loaders (*_load()) had returned FALSE in case of non-existent items. Now all *_load() functions should return NULL when the entity (or requested object) is not found.

Also, the load() method of your entity storage controllers (introduced in http://drupal.org/node/2032175) should return NULL when failing to retrieve the entity.

Entity loading wrapper

D7

function my_entity_load($id) {
  $entities = entity_load('my_entity', array($id));
  return $entities ? $entities[$id] : FALSE;
}

function my_entity_load_multiple($ids) {
  return entity_load('my_entity', $ids);
}

D8

Use YourEntity::load() and YourEntity::loadMultiple()

Controller loading method

D8

class MyEntityStorage extends EntityStorageBase {
  ...

  public function load($id) {
    // Do whatever you need to get your entity.
    ...
    
    return !empty($entity) ? $entity : NULL;
  }

  ...
}

Note: Only necessary when not relying on the default load() method.