Hello, I’m having this issue when I change between...

# compose

[Guilherme Delgado]

Hello, I’m having this issue when I change between dark/light theme:

java.lang.NullPointerException: Attempt to invoke virtual method 'androidx.navigation.NavDestination$DeepLinkMatch androidx.navigation.NavGraph.matchDeepLink(androidx.navigation.NavDeepLinkRequest)' on a null object reference

my setup is:

setContent {
    val navController = rememberNavController()
    NavHost(navController, startDestination = NavRouting.Home.destination) {
        composable(NavRouting.Home.destination) { ... }
        ...
    }
    navigationManager.commands.collectAsState().value.also { command ->
        if (command.destination.isNotEmpty()) {
            navController.navigate(command.destination) { launchSingleTop = true }
        }
    }
}

Regarding navigation events with MutableStateFlow I was inspired by Joe Birch post.
What am I doing wrong? 🤔 Thanks.

[Guilherme Delgado]

Well, if I add collectAsState(NavRouting.Idle) it fixes it, where NavRouting.Idle destination = “”

[Ian Lake]

Here's the previous thread about this same problem and an explanation on why Joe's approach is fundamentally flawed (you should not be treating Navigation events as state): https://kotlinlang.slack.com/archives/CJLTWPH7S/p1621016988041000?thread_ts=1621016988.041000&cid=CJLTWPH7S

[Guilherme Delgado]

Thanks Ian 🙏 , the NavRouting.Idle was a workaround because I couldn’t solve it, I didn’t remember about LaunchedEffect