Use lib.optionals instead of if then else [ ]

users/simon/modules/programs.nix

@@ -153,7 +153,7 @@ in
 
     # documents
     mupdf # document (pdf) viewer and tools
-  ] ++ (if config.sbruder.gui.enable then [
+  ] ++ lib.optionals config.sbruder.gui.enable [
     # communication
     claws-mail # email client that looks ugly but just works
     firefox-wayland # the least bad browser
@@ -206,5 +206,5 @@ in
     wl-clipboard # not really gui, but cli tool to manage wayland clipboard
     wxhexeditor # hex editor
     xfce.thunar # graphical file manager
-  ] else [ ]);
+  ];
 }