The website encountered an unexpected error. Please try again later.

I run library/drupal - Docker Hub (8.2.6) container and extend it with your module and as soon as I click on "Elasticsearch Connector (Administer Elasticsearch clusters and indices.)", I'm got following in my logs:

[Tue Feb 07 17:07:11.407141 2017] [:error] [pid 24] [client 10.52.208.221:34212] Error: Class 'nodespark\\DESConnector\\ClientFactory' not found in /var/www/html/core/lib/Drupal/Component/DependencyInjection/Container.php on line 264 #0 /var/www/html/core/lib/Drupal/Component/DependencyInjection/Container.php(177): Drupal\\Component\\DependencyInjection\\Container->createService(Array, 'elasticsearch_c...')\n#1 /var/www/html/core/lib/Drupal/Component/DependencyInjection/Container.php(494): Drupal\\Component\\DependencyInjection\\Container->get('elasticsearch_c...', 1)\n#2 /var/www/html/core/lib/Drupal/Component/DependencyInjection/Container.php(236): Drupal\\Component\\DependencyInjection\\Container->resolveServicesAndParameters(Array)\n#3 /var/www/html/core/lib/Drupal/Component/DependencyInjection/Container.php(177): Drupal\\Component\\DependencyInjection\\Container->createService(Array, 'elasticsearch_c...')\n#4 /var/www/html/modules/elasticsearch_connector/src/Controller/ClusterListBuilder.php(57): Drupal\\Component\\DependencyInjection\\Container->get('elasticsearch_c...')\n#5 /var/www/html/core/lib/Drupal/Core/Entity/EntityTypeManager.php(249): Drupal\\elasticsearch_connector\\Controller\\ClusterListBuilder::createInstance(Object(Drupal\\Core\\DependencyInjection\\Container), Object(Drupal\\Core\\Config\\Entity\\ConfigEntityType))\n#6 /var/www/html/core/lib/Drupal/Core/Entity/EntityTypeManager.php(238): Drupal\\Core\\Entity\\EntityTypeManager->createHandlerInstance('Drupal\\\\elastics...', Object(Drupal\\Core\\Config\\Entity\\ConfigEntityType))\n#7 /var/www/html/core/lib/Drupal/Core/Entity/EntityTypeManager.php(176): Drupal\\Core\\Entity\\EntityTypeManager->getHandler('elasticsearch_c...', 'list_builder')\n#8 /var/www/html/core/lib/Drupal/Core/Entity/EntityManager.php(73): Drupal\\Core\\Entity\\EntityTypeManager->getListBuilder('elasticsearch_c...')\n#9 /var/www/html/core/lib/Drupal/Core/Entity/Controller/EntityListController.php(22): Drupal\\Core\\Entity\\EntityManager->getListBuilder('elasticsearch_c...')\n#10 [internal function]: Drupal\\Core\\Entity\\Controller\\EntityListController->listing('elasticsearch_c...')\n#11 /var/www/html/core/lib/Drupal/Core/EventSubscriber/EarlyRenderingControllerWrapperSubscriber.php(123): call_user_func_array(Array, Array)\n#12 /var/www/html/core/lib/Drupal/Core/Render/Renderer.php(574): Drupal\\Core\\EventSubscriber\\EarlyRenderingControllerWrapperSubscriber->Drupal\\Core\\EventSubscriber\\{closure}()\n#13 /var/www/html/core/lib/Drupal/Core/EventSubscriber/EarlyRenderingControllerWrapperSubscriber.php(124): Drupal\\Core\\Render\\Renderer->executeInRenderContext(Object(Drupal\\Core\\Render\\RenderContext), Object(Closure))\n#14 /var/www/html/core/lib/Drupal/Core/EventSubscriber/EarlyRenderingControllerWrapperSubscriber.php(97): Drupal\\Core\\EventSubscriber\\EarlyRenderingControllerWrapperSubscriber->wrapControllerExecutionInRenderContext(Array, Array)\n#15 [internal function]: Drupal\\Core\\EventSubscriber\\EarlyRenderingControllerWrapperSubscriber->Drupal\\Core\\EventSubscriber\\{closure}()\n#16 /var/www/html/vendor/symfony/http-kernel/HttpKernel.php(144): call_user_func_array(Object(Closure), Array)\n#17 /var/www/html/vendor/symfony/http-kernel/HttpKernel.php(64): Symfony\\Component\\HttpKernel\\HttpKernel->handleRaw(Object(Symfony\\Component\\HttpFoundation\\Request), 1)\n#18 /var/www/html/core/lib/Drupal/Core/StackMiddleware/Session.php(57): Symfony\\Component\\HttpKernel\\HttpKernel->handle(Object(Symfony\\Component\\HttpFoundation\\Request), 1, true)\n#19 /var/www/html/core/lib/Drupal/Core/StackMiddleware/KernelPreHandle.php(47): Drupal\\Core\\StackMiddleware\\Session->handle(Object(Symfony\\Component\\HttpFoundation\\Request), 1, true)\n#20 /var/www/html/core/modules/page_cache/src/StackMiddleware/PageCache.php(99): Drupal\\Core\\StackMiddleware\\KernelPreHandle->handle(Object(Symfony\\Component\\HttpFoundation\\Request), 1, true)\n#21 /var/www/html/core/modules/page_cache/src/StackMiddleware/PageCache.php(78): Drupal\\page_cache\\StackMiddleware\\PageCache->pass(Object(Symfony\\Component\\HttpFoundation\\Request), 1, true)\n#22 /var/www/html/core/lib/Drupal/Core/StackMiddleware/ReverseProxyMiddleware.php(47): Drupal\\page_cache\\StackMiddleware\\PageCache->handle(Object(Symfony\\Component\\HttpFoundation\\Request), 1, true)\n#23 /var/www/html/core/lib/Drupal/Core/StackMiddleware/NegotiationMiddleware.php(50): Drupal\\Core\\StackMiddleware\\ReverseProxyMiddleware->handle(Object(Symfony\\Component\\HttpFoundation\\Request), 1, true)\n#24 /var/www/html/vendor/stack/builder/src/Stack/StackedHttpKernel.php(23): Drupal\\Core\\StackMiddleware\\NegotiationMiddleware->handle(Object(Symfony\\Component\\HttpFoundation\\Request), 1, true)\n#25 /var/www/html/core/lib/Drupal/Core/DrupalKernel.php(652): Stack\\StackedHttpKernel->handle(Object(Symfony\\Component\\HttpFoundation\\Request), 1, true)\n#26 /var/www/html/index.php(19): Drupal\\Core\\DrupalKernel->handle(Object(Symfony\\Component\\HttpFoundation\\Request))\n#27 {main}, referer: http://drupal.X.dev/admin/config
10.52.208.221 - - [07/Feb/2017:17:07:11 +0000] "GET /admin/config/search/elasticsearch-connector HTTP/1.1" 500 328 "http://drupal.X.dev/admin/config" "Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Firefox/45.0"

I didn't even get to Elasticsearch part...