Don't require nodes to have children

[andriokha]

Hi,

I started using this module on a site that has existing programs, program subcategories and activities, but that wasn't using classes and sessions. When trying to update existing activities I'm getting a fatal error.

Steps to reproduce

1. Ensure openy_repeat_nodes is active.
2. Create a published activity node without any associated classes.
3. Update the name of the activity node.

Results

The website encountered an unexpected error. Please try again later.

Drupal\Core\Entity\EntityStorageException: Query condition 'node__field_session_class.field_session_class_target_id IN ()' cannot be empty. in Drupal\Core\Entity\Sql\SqlContentEntityStorage->save() (line 815 of core/lib/Drupal/Core/Entity/Sql/SqlContentEntityStorage.php).
Drupal\Core\Database\Query\Select->condition('node__field_session_class.field_session_class_target_id', Array, 'IN') (Line: 77)
Drupal\Core\Entity\Query\Sql\Condition->compile(Object) (Line: 177)
Drupal\Core\Entity\Query\Sql\Query->compile() (Line: 81)
Drupal\Core\Entity\Query\Sql\Query->execute() (Line: 105)
openy_repeat_nodes_actualize_sessions(Object) (Line: 37)
openy_repeat_nodes_entity_update(Object)
call_user_func_array(Object, Array) (Line: 409)
Drupal\Core\Extension\ModuleHandler->Drupal\Core\Extension\{closure}(Object, 'openy_repeat_nodes') (Line: 388)
Drupal\Core\Extension\ModuleHandler->invokeAllWith('entity_update', Object) (Line: 416)
Drupal\Core\Extension\ModuleHandler->invokeAll('entity_update', Array) (Line: 217)
Drupal\Core\Entity\EntityStorageBase->invokeHook('update', Object) (Line: 900)
Drupal\Core\Entity\ContentEntityStorageBase->invokeHook('update', Object) (Line: 564)
Drupal\Core\Entity\EntityStorageBase->doPostSave(Object, 1) (Line: 781)
Drupal\Core\Entity\ContentEntityStorageBase->doPostSave(Object, 1) (Line: 489)
Drupal\Core\Entity\EntityStorageBase->save(Object) (Line: 804)
Drupal\Core\Entity\Sql\SqlContentEntityStorage->save(Object) (Line: 339)
Drupal\Core\Entity\EntityBase->save() (Line: 270)
Drupal\node\NodeForm->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('node_activity_edit_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: 163)
Symfony\Component\HttpKernel\HttpKernel->handleRaw(Object, 1) (Line: 74)
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: 58)
Drupal\openy_block_date\StackMiddleware\BlockDateCacheInvalidator->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: 51)
Drupal\Core\StackMiddleware\StackedHttpKernel->handle(Object, 1, 1) (Line: 692)
Drupal\Core\DrupalKernel->handle(Object) (Line: 19)