Re-add the getId method to the interface

src/Interface/SearchableInterface.php

@@ -6,6 +6,11 @@ namespace Pcm\SearchBundle\Interface;
 
 interface SearchableInterface
 {
+    /**
+     * This entity's ID.
+     */
+    public function getId(): ?int;
+
     /**
      * This entity's human-readable title to be shown in search results.
      */