The website encountered an unexpected error. Please try again later. AssertionError: Cannot load the "commerce_order_item_type" entity with NULL ID. in assert() (line 295 of core\lib\Drupal\Core\Entity\EntityStorageBase.php). assert(, 'Cannot load the "commerce_order_item_type" entity with NULL ID.') (Line: 295) Drupal\Core\Entity\EntityStorageBase->load(NULL) (Line: 488) Drupal\Core\Entity\EntityBase::load(NULL) (Line: 65) commerce_ticketing_form_commerce_product_variation_type_form_alter(Array, Object, 'commerce_product_variation_type_add_form') (Line: 562) Drupal\Core\Extension\ModuleHandler->alter('form', Array, Object, 'commerce_product_variation_type_add_form') (Line: 840) Drupal\Core\Form\FormBuilder->prepareForm('commerce_product_variation_type_add_form', Array, Object) (Line: 284) 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: 121) 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: 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: 718) Drupal\Core\DrupalKernel->handle(Object) (Line: 19)

这个错误可能是由于 Drupal Commerce 模块的一个 bug 导致的。尝试以下方法来解决这个问题：

1. 确认你已经安装了最新版本的 Drupal Commerce 模块，如果没有，请更新到最新版本。

2. 如果你已经安装了最新版本的 Drupal Commerce 模块，那么尝试卸载并重新安装 Commerce Order Item Type 模块。这个模块是 Commerce 模块的一部分，它定义了订单项类型。

3. 如果以上方法都无效，那么尝试禁用其他模块来确定是不是其他模块与 Commerce 模块冲突导致的问题。

希望这些方法能够帮助你解决这个问题。如果问题仍然存在，请查看 Drupal Commerce 模块的官方论坛以获取更多帮助。