fixes for oracle when updating to latest

modules/nixos/user.nix

@@ -5,6 +5,7 @@
     passwordHash = lib.mkOption {
       type = lib.types.nullOr lib.types.str;
       description = "Password created with mkpasswd -m sha-512";
+      default = null;
       # Test it by running: mkpasswd -m sha-512 --salt "PZYiMGmJIIHAepTM"
     };