tt-rss-module handle situations without any password

nixos/modules/services/web-apps/tt-rss.nix

@@ -22,7 +22,7 @@ let
       else if (cfg.database.passwordFile != null) then
         "file_get_contents('${cfg.database.passwordFile}')"
       else
-        ""
+        null
       ;
   in pkgs.writeText "config.php" ''
     <?php
@@ -40,7 +40,7 @@ let
       putenv('TTRSS_DB_HOST=${optionalString (cfg.database.host != null) cfg.database.host}');
       putenv('TTRSS_DB_USER=${cfg.database.user}');
       putenv('TTRSS_DB_NAME=${cfg.database.name}');
-      putenv('TTRSS_DB_PASS=' . ${password});
+      putenv('TTRSS_DB_PASS=' ${optionalString (password != null) ". ${password}"});
       putenv('TTRSS_DB_PORT=${toString dbPort}');
 
       putenv('TTRSS_AUTH_AUTO_CREATE=${boolToString cfg.auth.autoCreate}');