gnome-maps: fix broken .desktop file

pkgs/by-name/gn/gnome-maps/package.nix

@@ -5,7 +5,6 @@
   meson,
   ninja,
   gettext,
-  python3,
   pkg-config,
   gnome,
   glib,
@@ -75,8 +74,8 @@ stdenv.mkDerivation (finalAttrs: {
     # entry point to the wrapped binary we get back to a wrapped
     # binary.
     substituteInPlace "data/org.gnome.Maps.service.in" \
-        --replace "Exec=@pkgdatadir@/@app-id@" \
-                  "Exec=$out/bin/gnome-maps"
+      --replace-fail "Exec=@pkgdatadir@/@app-id@" \
+                     "Exec=$out/bin/gnome-maps"
   '';
 
   preCheck = ''
@@ -97,6 +96,12 @@ stdenv.mkDerivation (finalAttrs: {
     rm $out/lib/gnome-maps/libgnome-maps.so.0
   '';
 
+  preFixup = ''
+    substituteInPlace "$out/share/applications/org.gnome.Maps.desktop" \
+      --replace-fail "Exec=gapplication launch org.gnome.Maps" \
+                     "Exec=gnome-maps"
+  '';
+
   passthru = {
     updateScript = gnome.updateScript { packageName = "gnome-maps"; };
   };