I am trying type safety in Kotlin DSL and Navigation Compose but it looks like it is not working as expected, following is my code:

Screens:

@Serializable
data object SelectMenuNav

@Serializable
data class SelectProductNav(
    val menuSelection: MenuSelection
)

@Serializable
data class ProductDetailsNav(
    val menuSelection: MenuSelection,
    val product: Product
)

Custom Object I want to pass through composable

object CustomNavType {
    val ProductType = object : NavType<Product>(
        isNullableAllowed = false
    ) {
        override fun get(bundle: Bundle, key: String): Product? {
            return Json.decodeFromString(bundle.getString(key) ?: return null)
        }

        override fun parseValue(value: String): Product {
            return Json.decodeFromString(Uri.decode(value))
        }

        override fun put(bundle: Bundle, key: String, value: Product) {
            bundle.putString(key, Json.encodeToString(value))
        }

        override fun serializeAsValue(value: Product): String {
            return Uri.encode(Json.encodeToString(value))
        }
    }
}

My app navigation

@Composable
fun AppNavigation(modifier: Modifier = Modifier) {
    val navController = rememberNavController()
    NavHost(
        navController = navController,
        startDestination = SelectMenuNav
    ) {
        composable<SelectMenuNav> {
            ChooseMenuScreen(onSelection = { menuSelection ->
                navController.navigate(
                    SelectProductNav(
                        menuSelection = menuSelection
                    )
                )
            })
        }
        composable<SelectProductNav>(
            typeMap = mapOf(
                typeOf<MenuSelection>() to NavType.EnumType(MenuSelection::class.java)
            )
        ) {
            val menuSelection = it.toRoute<SelectProductNav>().menuSelection
            ChooseProductScreen(
                menuSelection = menuSelection,
                viewModel = hiltViewModel(),
                onNavigateToProductDetails = { product ->
                    navController.navigate(
                      ProductDetailsNav(
                          product = product,
                          menuSelection = menuSelection
                      )
                    )
                })
        }
        composable<ProductDetailsNav>(
            typeMap = mapOf(
                typeOf<Product>() to CustomNavType.ProductType,
                typeOf<MenuSelection>() to NavType.EnumType(MenuSelection::class.java)
            )
        ) { backStackEntry ->
            Log.d("AppNavigation", "ProductDetailsNav: ${backStackEntry.toRoute<ProductDetailsNav>()}")
            ProductDetailsScreen(
                modifier = Modifier,
                vm = hiltViewModel(),
                navigateToEditor = {},
                navigateBack = {}
            )
        }
    }
}

Even though Log is fine showing the product that has passed successfully between composables:

D  ProductDetailsNav: ProductDetailsNav(menuSelection=NAVA, product=Product(id=4371, productName=[...]

My viewmodel throws an error:

  java.lang.IllegalArgumentException: Route app.xml.aionianew.navigation.ProductDetailsNav could not find any NavType for argument product of type app.xml.aionianew.database.internal.data.Product - typeMap received was {}
                                                                                                        at androidx.navigation.serialization.RouteSerializerKt$generateNavArguments$2$1.invoke(RouteSerializer.kt:108)
                                                                                                        at androidx.navigation.serialization.RouteSerializerKt$generateNavArguments$2$1.invoke(RouteSerializer.kt:103)
                                                                                                        at androidx.navigation.NamedNavArgumentKt.navArgument(NamedNavArgument.kt:21)
                                                                                                        at androidx.navigation.serialization.RouteSerializerKt.generateNavArguments(RouteSerializer.kt:103)
                                                                                                        at androidx.navigation.SavedStateHandleKt.internalToRoute(SavedStateHandle.kt:50)
                                                                                                        at app.xml.aionianew.screens.product_details.ViewModelProductDetails.<init>(ViewModelProductDetails.kt:1018)
                                                                                                        at app.xml.aionianew.DaggerMyApp_HiltComponents_SingletonC$ViewModelCImpl$SwitchingProvider.get(DaggerMyApp_HiltComponents_SingletonC.java:497)
                                                                                                        at dagger.hilt.android.internal.lifecycle.HiltViewModelFactory$2.createViewModel(HiltViewModelFactory.java:133)

My code in viewmodel is like so:

@HiltViewModel
class ViewModelProductDetails @Inject constructor(
    private val uc: UseCasesProductDetails,
    savedState: SavedStateHandle
) : ViewModel() {

    private val selectedProduct: Product = savedState.toRoute<ProductDetailsNav>().product
    private val menuSelection:MenuSelection = savedState.toRoute<ProductDetailsNav>().menuSelection

So the question is what am I missing…