Add clone handler for Commerce products and variations

Number 35 custom module worked for me . . . select save product as cloned at bottom of Product Clone page. Get both the variations and Product, you'll need to edit the variation but it works

Changed core version to => core_version_requirement: ">=8" in info.yml

I spoke to soon. The custom module commerce entity clone throws the following error when a node is attempted to be cloned. Unistall of it solves it

The website encountered an unexpected error. Please try again later.
Error: Call to undefined method Drupal\node\Entity\Node::setVariations() in Drupal\commerce_entity_clone\EventSubscriber\ProductEntityCloneSubscriber->ProductEntityPreClone() (line 22 of modules/commerce_entity_clone/src/EventSubscriber/ProductEntityCloneSubscriber.php).
Drupal\commerce_entity_clone\EventSubscriber\ProductEntityCloneSubscriber->ProductEntityPreClone(Object, 'entity_clone.pre_clone', Object)
call_user_func(Array, Object, 'entity_clone.pre_clone', Object) (Line: 142)
Drupal\Component\EventDispatcher\ContainerAwareEventDispatcher->dispatch(Object, 'entity_clone.pre_clone') (Line: 342)
Drupal\entity_clone\Form\EntityCloneForm->submitForm(Array, Object)
call_user_func_array(Array, Array) (Line: 114)
Drupal\Core\Form\FormSubmitter->executeSubmitHandlers(Array, Object) (Line: 52)
Drupal\Core\Form\FormSubmitter->doSubmitForm(Array, Object) (Line: 597)
Drupal\Core\Form\FormBuilder->processForm('entity_clone_form', Array, Object) (Line: 325)
Drupal\Core\Form\FormBuilder->buildForm(Object, Object) (Line: 73)
Drupal\Core\Controller\FormController->getContentResult(Object, Object)
call_user_func_array(Array, Array) (Line: 123)
Drupal\Core\EventSubscriber\EarlyRenderingControllerWrapperSubscriber->Drupal\Core\EventSubscriber\{closure}() (Line: 580)
Drupal\Core\Render\Renderer->executeInRenderContext(Object, Object) (Line: 124)
Drupal\Core\EventSubscriber\EarlyRenderingControllerWrapperSubscriber->wrapControllerExecutionInRenderContext(Array, Array) (Line: 97)
Drupal\Core\EventSubscriber\EarlyRenderingControllerWrapperSubscriber->Drupal\Core\EventSubscriber\{closure}() (Line: 169)
Symfony\Component\HttpKernel\HttpKernel->handleRaw(Object, 1) (Line: 81)
Symfony\Component\HttpKernel\HttpKernel->handle(Object, 1, 1) (Line: 58)
Drupal\Core\StackMiddleware\Session->handle(Object, 1, 1) (Line: 48)
Drupal\Core\StackMiddleware\KernelPreHandle->handle(Object, 1, 1) (Line: 106)
Drupal\page_cache\StackMiddleware\PageCache->pass(Object, 1, 1) (Line: 85)
Drupal\page_cache\StackMiddleware\PageCache->handle(Object, 1, 1) (Line: 52)
Drupal\crawler_rate_limit\CrawlerRateLimitMiddleware->handle(Object, 1, 1) (Line: 57)
Drupal\advban\AdvbanMiddleware->handle(Object, 1, 1) (Line: 50)
Drupal\ban\BanMiddleware->handle(Object, 1, 1) (Line: 48)
Drupal\Core\StackMiddleware\ReverseProxyMiddleware->handle(Object, 1, 1) (Line: 51)
Drupal\Core\StackMiddleware\NegotiationMiddleware->handle(Object, 1, 1) (Line: 23)
Stack\StackedHttpKernel->handle(Object, 1, 1) (Line

Call to undefined method Drupal\node\Entity\Node::setVariations() in Drupal\commerce_entity_clone\EventSubscriber\ProductEntityCloneSubscriber->ProductEntityPreClone() (line 22 of modules/commerce_entity_clone/src/EventSubscriber/ProductEntityCloneSubscriber.php)

This issue can be fixed by wrapping the code inside the ProductEntityPreClone function:

public function ProductEntityPreClone(EntityCloneEvent $event) {
  $original = $event->getEntity();
  if ($original instanceof Product) {
    // The rest of the code.
  }
}

And also use the Product class at the top of the file:
use Drupal\commerce_product\Entity\Product;

Also, I found another issue: when the user wants to clone old Product, there is a chance that a newly generated SKU will be the same as the existing one (from one of the Products created later). Here's the fix for it:

$sku_query = $this->database->select('commerce_product_variation_field_data', 'v')
  ->fields('v', ['sku']);
  $sku_query_order = $sku_query->addExpression('CAST(sku as UNSIGNED)');
  $sku_query->orderBy($sku_query_order, 'DESC');
  $latest_sku_record = $sku_query->range(0, 1)->execute()->fetch();
  $new_sku = $latest_sku_record->sku + 1;

But the Connection should be added by the dependency injection in order to be used as $this->database.