"Notice: Undefined index: #value in validateElement()"

I just installed the module and added the field as part of one paragraph attached to a content type.
Every time I save a node of the content type, the following message is displayed. The attached patch is fixing this small issue.

Notice: Undefined index: #value in Drupal\multiple_selects\Plugin\Field\FieldWidget\OptionsMultipleSelectWidget::validateElement() (line 44 of modules/contrib/multiple_selects/src/Plugin/Field/FieldWidget/OptionsMultipleSelectWidget.php).
Drupal\multiple_selects\Plugin\Field\FieldWidget\OptionsMultipleSelectWidget::validateElement(Array, Object, Array)
call_user_func_array(Array, Array) (Line: 282)
Drupal\Core\Form\FormValidator->doValidateForm(Array, Object) (Line: 238)
Drupal\Core\Form\FormValidator->doValidateForm(Array, Object) (Line: 238)
Drupal\Core\Form\FormValidator->doValidateForm(Array, Object) (Line: 238)
Drupal\Core\Form\FormValidator->doValidateForm(Array, Object) (Line: 238)
Drupal\Core\Form\FormValidator->doValidateForm(Array, Object) (Line: 238)
Drupal\Core\Form\FormValidator->doValidateForm(Array, Object) (Line: 238)
Drupal\Core\Form\FormValidator->doValidateForm(Array, Object) (Line: 238)
Drupal\Core\Form\FormValidator->doValidateForm(Array, Object, 'node_home_page_edit_form') (Line: 118)
Drupal\Core\Form\FormValidator->validateForm('node_home_page_edit_form', Array, Object) (Line: 575)
Drupal\Core\Form\FormBuilder->processForm('node_home_page_edit_form', Array, Object) (Line: 318)
Drupal\Core\Form\FormBuilder->buildForm('node_home_page_edit_form', Object) (Line: 93)
Drupal\Core\Controller\FormController->getContentResult(Object, Object)
call_user_func_array(Array, Array) (Line: 123)
Drupal\Core\EventSubscriber\EarlyRenderingControllerWrapperSubscriber->Drupal\Core\EventSubscriber\{closure}() (Line: 582)
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: 151)
Symfony\Component\HttpKernel\HttpKernel->handleRaw(Object, 1) (Line: 68)
Symfony\Component\HttpKernel\HttpKernel->handle(Object, 1, 1) (Line: 57)
Drupal\Core\StackMiddleware\Session->handle(Object, 1, 1) (Line: 47)
Drupal\Core\StackMiddleware\KernelPreHandle->handle(Object, 1, 1) (Line: 99)
Drupal\page_cache\StackMiddleware\PageCache->pass(Object, 1, 1) (Line: 78)
Drupal\page_cache\StackMiddleware\PageCache->handle(Object, 1, 1) (Line: 47)
Drupal\Core\StackMiddleware\ReverseProxyMiddleware->handle(Object, 1, 1) (Line: 52)
Drupal\Core\StackMiddleware\NegotiationMiddleware->handle(Object, 1, 1) (Line: 23)
Stack\StackedHttpKernel->handle(Object, 1, 1) (Line: 665)
Drupal\Core\DrupalKernel->handle(Object) (Line: 19)