Error when creating a product

I create a product entity instance like below. However, it results in : "Recoverable fatal error: Argument 1 passed to Drupal\commerce_order\OrderItemStorage::createFromPurchasableEntity()
must implement interface Drupal\commerce\PurchasableEntityInterface, null given". I'm missing how to implement PurchasableEntityInterface.

How to complete this correctly? Thanks.

use Drupal\commerce_product\Entity\Product;
use Drupal\commerce\PurchasableEntityInterface;

$my_product = Product::create([
  'type' => 'food',
  'langcode' => 'en',
  'created' => REQUEST_TIME,
  'changed' => REQUEST_TIME,
  'uid' => 1,
  'title' => 'My product',
  'body' => [
    'summary' => '',
    'value' => '<p>Lorem Ipsum</p>',
    'format' => 'full_html',
  ],
]);
$my_product->save();