fix

module.nix

@@ -166,6 +166,7 @@ in
           POSTGRES_DBNAME = db.name;
           POSTGRES_USER = db.user;
           POSTGRES_HOST = db.host;
+          USERDATA_FILE_PATH = "/var/lib/mastodon/.userdata.json";
         };
         serviceConfig = {
           Slice = "mastodon.slice";