🐛 Properly reference \Exception when trying to create index.

src/ElasticsearchEngine.php

@@ -282,7 +282,7 @@ public function lazyMap(Builder $builder, $results, $model)
      */
     public function createIndex($name, array $options = [])
     {
-        throw new Exception('Database indexes are created automatically upon adding objects.');
+        throw new \Exception('Database indexes are created automatically upon adding objects.');
     }
 
     /**