Drupal 8.0.0 beta 12. More info: https://www.drupal.org/node/2514176

core/modules/config/src/ConfigSubscriber.php

@@ -0,0 +1,42 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\config\ConfigSubscriber.
+ */
+
+namespace Drupal\config;
+
+use Drupal\Core\Config\ConfigEvents;
+use Drupal\Core\Config\ConfigImporterEvent;
+use Drupal\Core\Config\ConfigImporterException;
+use Drupal\Core\Config\ConfigImportValidateEventSubscriberBase;
+
+
+/**
+ * Config subscriber.
+ */
+class ConfigSubscriber extends ConfigImportValidateEventSubscriberBase {
+
+  /**
+   * Checks that the Configuration module is not being uninstalled.
+   *
+   * @param ConfigImporterEvent $event
+   *   The config import event.
+   */
+  public function onConfigImporterValidate(ConfigImporterEvent $event) {
+    $importer = $event->getConfigImporter();
+    $core_extension = $importer->getStorageComparer()->getSourceStorage()->read('core.extension');
+    if (!isset($core_extension['module']['config'])) {
+      $importer->logError($this->t('Can not uninstall the Configuration module as part of a configuration synchronization through the user interface.'));
+    }
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  static function getSubscribedEvents() {
+    $events[ConfigEvents::IMPORT_VALIDATE][] = array('onConfigImporterValidate', 20);
+    return $events;
+  }
+}