Issue #2536510: Fix error on webhooks page when API calls fail.

   * {@inheritdoc}

   */

  public function buildForm(array $form, FormStateInterface $form_state) {

    try {

      $client = shopify_api_client();

      $webhooks = $client->getResources('webhooks');

    } catch (\Exception $e) {

      // Error connecting to the store.

      drupal_set_message(t('Could not connect to the Shopify store.'), 'error');

      return [];

    }

    $config = $this->config('shopify.webhooks');

    $form['#tree'] = TRUE;