I am working on a project that utilizes Jetpack Compose Navigation with Type-Safe Navigation. Within my application, I have an composable function responsible for hosting the navigation graph. Here’s a simplified version of the code:

@Composable
fun Content(
    mainNavController: NavController = rememberNavController()
) {
    val currentBackStackEntry by mainNavController.currentBackStackEntryAsState()
    val currentRoute = currentBackStackEntry?.toRoute<Route>()
}

@Serializable
sealed interface Route {
    @Serializable
    data object Route1 : Route

    @Serializable
    data object Route2 : Route

    @Serializable
    data object Route3 : Route
}

I’m attempting to retrieve the current route object outside the composable<> block. However, I encounter the following exception:

IllegalArgumentException: Polymorphic value has not been read for class null

It appears that polymorphic behavior is not supported in this context. Can someone provide guidance on how to solve this issue? I need to be able to obtain the current route object outside the NavHost composable<> block using toRoute function. Thank you!