Format Views Contact Form Error

It seems there is no handler for null entity and initial value of contact_type is null.

public function settingsSummary() {
    $summary = [];

    $entity = ContactForm::load($this->getSetting('contact_type'));
    $contact_recipients_include = $this->getSetting('contact_recipients_include') == TRUE ? 'Yes' : 'No';

    $summary[] = t('Contact: <a href="@url">@contact_label</a>',
    [
      '@url' => '/admin/structure/contact/manage/' . $entity->get('id'),
      '@contact_label' => $entity->get('label'),
    ]);
    $summary[] = t('Include contact form recipient(s): @contact_recipients_include',
    ['@contact_recipients_include' => $contact_recipients_include]);

    return $summary;
  }