Error message

• Warning: Undefined array key 0 in cactus_preprocess_node() (line 836 of themes/custom/cactus/cactus.theme).

  cactus_preprocess_node(Array, 'node', Array)
  call_user_func_array('cactus_preprocess_node', Array) (Line: 261)
  Drupal\Core\Theme\ThemeManager->render('node', Array) (Line: 480)
  Drupal\Core\Render\Renderer->doRender(Array, ) (Line: 240)
  Drupal\Core\Render\Renderer->render(Array, ) (Line: 238)
  Drupal\Core\Render\MainContent\HtmlRenderer->Drupal\Core\Render\MainContent\{closure}() (Line: 627)
  Drupal\Core\Render\Renderer->executeInRenderContext(Object, Object) (Line: 239)
  Drupal\Core\Render\MainContent\HtmlRenderer->prepare(Array, Object, Object) (Line: 128)
  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(Object, 'kernel.view') (Line: 186)
  Symfony\Component\HttpKernel\HttpKernel->handleRaw(Object, 1) (Line: 76)
  Symfony\Component\HttpKernel\HttpKernel->handle(Object, 1, 1) (Line: 43)
  Drupal\force_password_change\Service\ForcePasswordChangeRedirectMiddleware->handle(Object, 1, 1) (Line: 68)
  Drupal\simple_oauth\HttpMiddleware\BasicAuthSwap->handle(Object, 1, 1) (Line: 58)
  Drupal\Core\StackMiddleware\Session->handle(Object, 1, 1) (Line: 48)
  Drupal\Core\StackMiddleware\KernelPreHandle->handle(Object, 1, 1) (Line: 28)
  Drupal\Core\StackMiddleware\ContentLength->handle(Object, 1, 1) (Line: 50)
  Drupal\ban\BanMiddleware->handle(Object, 1, 1) (Line: 263)
  Drupal\shield\ShieldMiddleware->bypass(Object, 1, 1) (Line: 130)
  Drupal\shield\ShieldMiddleware->handle(Object, 1, 1) (Line: 48)
  Drupal\Core\StackMiddleware\ReverseProxyMiddleware->handle(Object, 1, 1) (Line: 51)
  Drupal\Core\StackMiddleware\NegotiationMiddleware->handle(Object, 1, 1) (Line: 36)
  Drupal\Core\StackMiddleware\AjaxPageState->handle(Object, 1, 1) (Line: 49)
  Drupal\remove_http_headers\StackMiddleware\RemoveHttpHeadersMiddleware->handle(Object, 1, 1) (Line: 51)
  Drupal\Core\StackMiddleware\StackedHttpKernel->handle(Object, 1, 1) (Line: 704)
  Drupal\Core\DrupalKernel->handle(Object) (Line: 19)
  

• Warning: Trying to access array offset on value of type null in cactus_preprocess_node() (line 836 of themes/custom/cactus/cactus.theme).

  cactus_preprocess_node(Array, 'node', Array)
  call_user_func_array('cactus_preprocess_node', Array) (Line: 261)
  Drupal\Core\Theme\ThemeManager->render('node', Array) (Line: 480)
  Drupal\Core\Render\Renderer->doRender(Array, ) (Line: 240)
  Drupal\Core\Render\Renderer->render(Array, ) (Line: 238)
  Drupal\Core\Render\MainContent\HtmlRenderer->Drupal\Core\Render\MainContent\{closure}() (Line: 627)
  Drupal\Core\Render\Renderer->executeInRenderContext(Object, Object) (Line: 239)
  Drupal\Core\Render\MainContent\HtmlRenderer->prepare(Array, Object, Object) (Line: 128)
  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(Object, 'kernel.view') (Line: 186)
  Symfony\Component\HttpKernel\HttpKernel->handleRaw(Object, 1) (Line: 76)
  Symfony\Component\HttpKernel\HttpKernel->handle(Object, 1, 1) (Line: 43)
  Drupal\force_password_change\Service\ForcePasswordChangeRedirectMiddleware->handle(Object, 1, 1) (Line: 68)
  Drupal\simple_oauth\HttpMiddleware\BasicAuthSwap->handle(Object, 1, 1) (Line: 58)
  Drupal\Core\StackMiddleware\Session->handle(Object, 1, 1) (Line: 48)
  Drupal\Core\StackMiddleware\KernelPreHandle->handle(Object, 1, 1) (Line: 28)
  Drupal\Core\StackMiddleware\ContentLength->handle(Object, 1, 1) (Line: 50)
  Drupal\ban\BanMiddleware->handle(Object, 1, 1) (Line: 263)
  Drupal\shield\ShieldMiddleware->bypass(Object, 1, 1) (Line: 130)
  Drupal\shield\ShieldMiddleware->handle(Object, 1, 1) (Line: 48)
  Drupal\Core\StackMiddleware\ReverseProxyMiddleware->handle(Object, 1, 1) (Line: 51)
  Drupal\Core\StackMiddleware\NegotiationMiddleware->handle(Object, 1, 1) (Line: 36)
  Drupal\Core\StackMiddleware\AjaxPageState->handle(Object, 1, 1) (Line: 49)
  Drupal\remove_http_headers\StackMiddleware\RemoveHttpHeadersMiddleware->handle(Object, 1, 1) (Line: 51)
  Drupal\Core\StackMiddleware\StackedHttpKernel->handle(Object, 1, 1) (Line: 704)
  Drupal\Core\DrupalKernel->handle(Object) (Line: 19)