On node edit form Warning: Undefined variable $field_settings in Drupal\yearonly\Plugin\Field\FieldWidget\YearOnlyDefaultWidget->formElement()

Problem/Motivation

Warning: Undefined variable $field_settings in Drupal\yearonly\Plugin\Field\FieldWidget\YearOnlyDefaultWidget->formElement() (line 71 of modules/contrib/yearonly/src/Plugin/Field/FieldWidget/YearOnlyDefaultWidget.php).
Drupal\yearonly\Plugin\Field\FieldWidget\YearOnlyDefaultWidget->formElement() (Line: 459)
Drupal\Core\Field\WidgetBase->formSingleElement() (Line: 219)
Drupal\Core\Field\WidgetBase->formMultipleElements() (Line: 120)
Drupal\Core\Field\WidgetBase->form() (Line: 190)
Drupal\Core\Entity\Entity\EntityFormDisplay->buildForm() (Line: 121)
Drupal\Core\Entity\ContentEntityForm->form() (Line: 134)
Drupal\node\NodeForm->form() (Line: 107)
Drupal\Core\Entity\EntityForm->buildForm()
call_user_func_array() (Line: 536)
Drupal\Core\Form\FormBuilder->retrieveForm() (Line: 284)
Drupal\Core\Form\FormBuilder->buildForm() (Line: 73)
Drupal\Core\Controller\FormController->getContentResult() (Line: 39)
Drupal\layout_builder\Controller\LayoutBuilderHtmlEntityFormController->getContentResult()
call_user_func_array() (Line: 123)
Drupal\Core\EventSubscriber\EarlyRenderingControllerWrapperSubscriber->Drupal\Core\EventSubscriber\{closure}() (Line: 638)
Drupal\Core\Render\Renderer->executeInRenderContext() (Line: 124)
Drupal\Core\EventSubscriber\EarlyRenderingControllerWrapperSubscriber->wrapControllerExecutionInRenderContext() (Line: 97)
Drupal\Core\EventSubscriber\EarlyRenderingControllerWrapperSubscriber->Drupal\Core\EventSubscriber\{closure}() (Line: 181)
Symfony\Component\HttpKernel\HttpKernel->handleRaw() (Line: 76)
Symfony\Component\HttpKernel\HttpKernel->handle() (Line: 53)
Drupal\Core\StackMiddleware\Session->handle() (Line: 48)
Drupal\Core\StackMiddleware\KernelPreHandle->handle() (Line: 28)
Drupal\Core\StackMiddleware\ContentLength->handle() (Line: 32)
Drupal\big_pipe\StackMiddleware\ContentLength->handle() (Line: 116)
Drupal\page_cache\StackMiddleware\PageCache->pass() (Line: 90)
Drupal\page_cache\StackMiddleware\PageCache->handle() (Line: 48)
Drupal\Core\StackMiddleware\ReverseProxyMiddleware->handle() (Line: 51)
Drupal\Core\StackMiddleware\NegotiationMiddleware->handle() (Line: 36)
Drupal\Core\StackMiddleware\AjaxPageState->handle() (Line: 51)
Drupal\Core\StackMiddleware\StackedHttpKernel->h

Steps to reproduce

Proposed resolution

Remaining tasks

User interface changes

API changes

Data model changes