Controller fails for external data sources

I'm not sure about this. This makes the controller not use entity rendering anymore. So that would be a regression vs the current behavior.

  /**
   * {@inheritdoc}
   */
  public function viewItem(ComplexDataInterface $item, $view_mode, $langcode = NULL) {
    try {
      if ($entity = $this->getEntity($item)) {
        $langcode = $langcode ?: $entity->language()->getId();
        return $this->getEntityTypeManager()->getViewBuilder($this->getEntityTypeId())->view($entity, $view_mode, $langcode);
      }
    }
    catch (\Exception $e) {
      // The most common reason for this would be a
      // \Drupal\Component\Plugin\Exception\InvalidPluginDefinitionException in
      // getViewBuilder(), because the entity type definition doesn't specify a
      // view_builder class.
    }
    return [];
  }

It looks like the viewItem method actually does render the entity using entity rendering, but falls back to an empty array if that's not possible. The suggested change would make things more robust if that's actually the case, so let's see what testbot thinks of it, but with a correct patch this time.

Testbot doesn't seem to mind. What do you think borisson_?

Testbot here isn't to be as trusted as in the Search API module, but it does look good. I forgot about viewItem's behavior.

This patch no longer applies

Rerolled

Back to RTBC, will commit over the weekend or during dev days.

Committed and pushed, thanks!