Issue #3314315 by e0ipso: Useful error message for disabled providers

namespace Drupal\cl_server\Controller;

use Drupal\cl_components\Plugin\Component;

use Drupal\cl_components\ComponentPluginManager;

use Drupal\cl_components\Exception\ComponentNotFoundException;

use Drupal\cl_components\Exception\TemplateNotFoundException;

use Drupal\cl_components\Plugin\Component;

use Drupal\Component\Serialization\Json;

use Drupal\Core\Controller\ControllerBase;

use Drupal\Core\PageCache\ResponsePolicy\KillSwitch;

    $arguments = $this->getArguments($request);

    try {

      $component = $this->getComponent($request);

    }

    catch (ComponentNotFoundException $e) {

      throw new BadRequestHttpException('Invalid component', $e);

    }

      $variant = $request->query->get('_variant');

      // Storybook will not allow empty title for the story. Let's consider

      // Default to be the default.

      $variant = $variant === 'default' ? '' : $variant ?? '';

    try {

      $build = $this->generateRenderArray($component, $variant ?: '', $arguments);

    }

    catch (TemplateNotFoundException $e) {

      $build = [];

    catch (ComponentNotFoundException|TemplateNotFoundException $e) {

      $build = [

        '#markup' => '<div class="messages messages--error"><h3>' . $this->t('Unable to find component') . '</h3>' . $this->t('Check that the module or theme containing the component is enabled and matches the stories file name.') . '</div>',

      ];

    }

    $this->cacheKillSwitch->trigger();

    return [