add whatsapp app to darwin

nix/system/worktop/makeApp.nix

@@ -7,20 +7,13 @@
   pkgs
 , stdenv
 , unzip
-, ...
-}:
-if stdenv.isDarwin then
-  pkgs.stdenv.mkDerivation
-  {
-    name = "${name}-${version}";
-    version = "${version}";
-    src = src;
+, unpackCmd ? ''
+      echo "File to unpack: $curSrc";
+    if ! [[ "$curSrc" =~ \.dmg$ ]]; then
+      echo "Not a .dmg, cannot unpack"
+      return 1;
+    fi
 
-    sourceRoot = "${appname}.app";
-    phases = [ "unpackPhase" "installPhase" ];
-    unpackCmd = ''
-      echo "File to unpack: $curSrc"
-      if ! [[ "$curSrc" =~ \.dmg$ ]]; then return 1; fi
       mnt=$(mktemp -d -t ci-XXXXXXXXXX)
 
       function finish {
@@ -40,7 +33,19 @@ if stdenv.isDarwin then
       shopt -s extglob
       DEST="$PWD"
       (cd "$mnt"; cp -a !(Applications) "$DEST/")
-    '';
+  ''
+, ...
+}:
+if stdenv.isDarwin then
+  pkgs.stdenv.mkDerivation
+  {
+    name = "${name}-${version}";
+    version = "${version}";
+    src = src;
+
+    sourceRoot = "${appname}.app";
+    phases = [ "unpackPhase" "installPhase" ];
+    unpackCmd = unpackCmd;
     nativeBuildInputs = [ pkgs.unzip ];
     installPhase = ''
       mkdir -p $out/Applications/${appname}.app