Error: buildExcludedPlugins() must be of the type array on import the incorrect settings

The following error is shown at /admin/structure/webform/settings:

The website encountered an unexpected error. Please try again later.
TypeError: Argument 2 passed to Drupal\webform\Form\WebformAdminSettingsForm::buildExcludedPlugins() must be of the type array, null given, called in modules/contrib/webform/src/Form/WebformAdminSettingsForm.php on line 690 in Drupal\webform\Form\WebformAdminSettingsForm->buildExcludedPlugins() (line 1218 of modules/contrib/webform/src/Form/WebformAdminSettingsForm.php).
Drupal\webform\Form\WebformAdminSettingsForm->buildExcludedPlugins(Object, NULL) (Line: 690)
Drupal\webform\Form\WebformAdminSettingsForm->buildForm(Array, Object)
call_user_func_array(Array, Array) (Line: 514)
Drupal\Core\Form\FormBuilder->retrieveForm('webform_admin_settings_form', Object) (Line: 271)
Drupal\Core\Form\FormBuilder->buildForm('webform_admin_settings_form', Object) (Line: 74)
Drupal\Core\Controller\FormController->getContentResult(Object, Object)
call_user_func_array(Array, Array) (Line: 123)
Drupal\Core\EventSubscriber\EarlyRenderingControllerWrapperSubscriber->Drupal\Core\EventSubscriber\{closure}() (Line: 574)
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}()
call_user_func_array(Object, Array) (Line: 144)
Symfony\Component\HttpKernel\HttpKernel->handleRaw(Object, 1) (Line: 64)
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: 50)
Drupal\Core\StackMiddleware\NegotiationMiddleware->handle(Object, 1, 1) (Line: 23)
Stack\StackedHttpKernel->handle(Object, 1, 1) (Line: 656)
Drupal\Core\DrupalKernel->handle(Object) (Line: 19)

This is likely related to the incorrect settings in config/sync/webform.settings.yml, e.g.

Breaks on:

excluded_types: { }

but it should be:

excluded_elements: { }

Looks like an old/manual export setting cause the problem (this prevented submission of forms with attachments).