Merge pull request #24601 from pbogdan/unclutter

unclutter: Fix default value of $DISPLAY

nixos/modules/services/x11/unclutter.nix

@@ -60,7 +60,10 @@ in {
       serviceConfig.ExecStart = ''
         ${cfg.package}/bin/unclutter \
           -idle ${toString cfg.timeout} \
-          -display :${toString config.services.xserver.display} \
+          -display :${toString (
+             let display = config.services.xserver.display;
+             in if display != null then display else 0
+          )} \
           -jitter ${toString (cfg.threeshold - 1)} \
           ${optionalString cfg.keystroke "-keystroke"} \
           ${concatMapStrings (x: " -"+x) cfg.extraOptions} \