Go router Optional pathParameters

In StackOverflow, you can access question through two different URL

• https://stackoverflow.com/questions/:questionId/:slug
• https://stackoverflow.com/questions/:questionId

I am trying to build the Same.

  GoRoute(
            path: "${LeaderboardItemPage.route}/:creationId",
            name: LeaderboardItemPage.route,
            redirect: (
              context,
              state,
            ) {
              final creationId = state.pathParameters['creationId'];
              return "${LeaderboardItemPage.route}/$creationId/overview";
            },
            routes: [
              /// same as a
              GoRoute(
                path: ":slug",
                // pag
                // name: LeaderboardItemPage.route,
                builder: (BuildContext context, GoRouterState state) {
                  final creationId = state.pathParameters['creationId'];
                  final slug = state.pathParameters['slug'];
                  print("Slug: $slug");
                  if (creationId == null) {
                    return ErrorWidget();
                  }
                  return LeaderboardItemPage(
                    creationId: creationId,
                  );
                },
              ),
            ],
          ),

This barely works, but has lots of issue. First of all , I am forcing a dummy slug called overview . What if I actually want it to be null and show a popup to the user asking to create a permalink ?

Secondly,

 context.pushNamed(LeaderboardItemPage.route, pathParameters: {
      'creationId': leaderboardItem.creationId,
      'slug' : "some-slug"
    });
    return;

I get unknown param "slug" for /creations/:creationId. I want to use the same routeName for both and still use the pathParameters, not direct url