the topbar is not displaying properly. about compose-destinations HOT 1 CLOSED

I found an issue while trying to use it, the topbar is not displaying properly.

`@Composable fun RallyApp() { RallyTheme { val navController = rememberNavController() val currentBackStackEntryAsState by navController.currentBackStackEntryAsState() val destination = currentBackStackEntryAsState?.destination

    var currentScreen = rallyTabRowScreens.find {
        it.route == destination?.route
    }
    var isShowBackButton by rememberSaveable {
        mutableStateOf(false)
    }
    isShowBackButton = currentScreen == null
    Scaffold(
        topBar = {
            if (currentScreen != null) {
                RallyTabRow(
                    allScreens = rallyTabRowScreens,
                    onTabSelected = { screen ->
                        navController.navigateSingleTop(screen.route)
                    },
                    currentScreen = currentScreen
                )
            }
        }
    ) { innerPadding ->
        DestinationsNavHost(navGraph = NavGraphs.root , modifier = Modifier.padding(innerPadding))
    }
}

}`

from compose-destinations.