Creating a webform submission relationship is not possible

Creating a webform submission relationship is not possible and throws the following error on 9.5.9 with PHP 8.1.16:

Drupal\Core\Config\Schema\SchemaIncompleteException: Entity type 'Drupal\webform_views_extras\Entity\WebformSubmissionRelationships' is missing 'config_export' definition in its annotation in Drupal\Core\Config\Entity\ConfigEntityBase->toArray() (line 253 of core/lib/Drupal/Core/Config/Entity/ConfigEntityBase.php).
Drupal\Core\Entity\Plugin\DataType\EntityAdapter->toArray() (Line: 750)
we_megamenu_entity_presave(Object, 'webform_submission_relationships')
call_user_func_array(Object, Array) (Line: 426)
Drupal\Core\Extension\ModuleHandler->Drupal\Core\Extension\{closure}(Object, 'we_megamenu') (Line: 405)
Drupal\Core\Extension\ModuleHandler->invokeAllWith('entity_presave', Object) (Line: 433)
Drupal\Core\Extension\ModuleHandler->invokeAll('entity_presave', Array) (Line: 339)
Drupal\Core\Config\Entity\ConfigEntityStorage->invokeHook('presave', Object) (Line: 563)
Drupal\Core\Entity\EntityStorageBase->doPreSave(Object) (Line: 517)
Drupal\Core\Entity\EntityStorageBase->save(Object) (Line: 253)
Drupal\Core\Config\Entity\ConfigEntityStorage->save(Object) (Line: 339)
Drupal\Core\Entity\EntityBase->save() (Line: 608)
Drupal\Core\Config\Entity\ConfigEntityBase->save() (Line: 99)
Drupal\webform_views_extras\Form\WebformSubmissionRelationshipsForm->save(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('webform_submission_relationships_add_form', Array, Object) (Line: 325)
Drupal\Core\Form\FormBuilder->buildForm(Object, Object) (Line: 73)
Drupal\Core\Controller\FormController->getContentResult(Object, Object) (Line: 39)
Drupal\layout_builder\Controller\LayoutBuilderHtmlEntityFormController->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: 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)

any ideas?