Issue #3199156 by mkalkbrenner: Drupal site install from existing config is broken

Closes #3199156

src/EventSubscriber/SearchApiSubscriber.php

@@ -49,6 +49,12 @@ class SearchApiSubscriber implements EventSubscriberInterface {
    * {@inheritdoc}
    */
   public static function getSubscribedEvents() {
+    // Workaround to avoid a fatal error during site install from existing config.
+    // @see https://www.drupal.org/project/facets/issues/3199156
+    if (!class_exists('\Drupal\search_api\Event\SearchApiEvents', TRUE)) {
+      return [];
+    }
+
     return [
       SearchApiEvents::QUERY_PRE_EXECUTE => 'queryAlter',
     ];