Error message

• Error in retrieving lists.
• Warning: count(): Parameter must be an array or an object that implements Countable in Drupal\Core\Render\Element\Checkboxes::processCheckboxes() (line 58 of core/lib/Drupal/Core/Render/Element/Checkboxes.php).

  Drupal\Core\Render\Element\Checkboxes::processCheckboxes(Array, Object, Array)
  call_user_func_array(Array, Array) (Line: 1008)
  Drupal\Core\Form\FormBuilder->doBuildForm('exact_target_newsletter_ajax_form', Array, Object) (Line: 1071)
  Drupal\Core\Form\FormBuilder->doBuildForm('exact_target_newsletter_ajax_form', Array, Object) (Line: 575)
  Drupal\Core\Form\FormBuilder->processForm('exact_target_newsletter_ajax_form', Array, Object) (Line: 321)
  Drupal\Core\Form\FormBuilder->buildForm('Drupal\exact_target\Form\NewsLetterAjaxForm', Object) (Line: 219)
  Drupal\Core\Form\FormBuilder->getForm('Drupal\exact_target\Form\NewsLetterAjaxForm') (Line: 31)
  getSubscriptionForm() (Line: 20)
  exact_target_preprocess_page(Array, 'page', Array) (Line: 287)
  Drupal\Core\Theme\ThemeManager->render('page', Array) (Line: 431)
  Drupal\Core\Render\Renderer->doRender(Array, ) (Line: 200)
  Drupal\Core\Render\Renderer->render(Array) (Line: 501)
  Drupal\Core\Template\TwigExtension->escapeFilter(Object, Array, 'html', NULL, 1) (Line: 103)
  __TwigTemplate_3d770f4aa981b58cab43717bd9e445f626481ce36550cbe5f1c95a6ade256ff8->doDisplay(Array, Array) (Line: 455)
  Twig\Template->displayWithErrorHandling(Array, Array) (Line: 422)
  Twig\Template->display(Array) (Line: 434)
  Twig\Template->render(Array) (Line: 64)
  twig_render_template('themes/custom/bootstrap_tsnn_corp/templates/html.html.twig', Array) (Line: 384)
  Drupal\Core\Theme\ThemeManager->render('html', Array) (Line: 431)
  Drupal\Core\Render\Renderer->doRender(Array, ) (Line: 200)
  Drupal\Core\Render\Renderer->render(Array) (Line: 147)
  Drupal\Core\Render\MainContent\HtmlRenderer->Drupal\Core\Render\MainContent\{closure}() (Line: 573)
  Drupal\Core\Render\Renderer->executeInRenderContext(Object, Object) (Line: 148)
  Drupal\Core\Render\MainContent\HtmlRenderer->renderResponse(Array, Object, Object) (Line: 90)
  Drupal\Core\EventSubscriber\MainContentViewSubscriber->onViewRenderArray(Object, 'kernel.view', Object)
  call_user_func(Array, Object, 'kernel.view', Object) (Line: 111)
  Drupal\Component\EventDispatcher\ContainerAwareEventDispatcher->dispatch('kernel.view', Object) (Line: 156)
  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: 191)
  Drupal\page_cache\StackMiddleware\PageCache->fetch(Object, 1, 1) (Line: 128)
  Drupal\page_cache\StackMiddleware\PageCache->lookup(Object, 1, 1) (Line: 82)
  Drupal\page_cache\StackMiddleware\PageCache->handle(Object, 1, 1) (Line: 50)
  Drupal\ban\BanMiddleware->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: 708)
  Drupal\Core\DrupalKernel->handle(Object) (Line: 19)