Cannot handle exception in firebase function-CodePudding

i'm trying to understand with no luck why this throwable is not catched in my catch block:

CoroutineScope(IO).launch {
        try {   FirebaseMessaging.getInstance().token.addOnCompleteListener(OnCompleteListener { task ->
                if (task.isSuccessful) {
                    token = task.result
                }
                throw Exception("Hi There!")
            }).await()
            getUsers().await()
        }catch (e: Exception){
           binding.txtTitle.text = "Error: ${e.message}"
        }
    }

The exception is called but the app crash and not handle by the catch block. But if i throw an exception outside the addOnCompleteListener the exception is handled normally. My objective is to stop the execution of the getUsers function if no token is available.

CodePudding user response：

The exception which is thrown in OnCompleteListener will not propagate to the outer scope, it is scoped to OnCompleteListener block. To achieve your objective I would recommend to rewrite the code to something like the following:

coroutineScope.launch {
    try {
        val token: String = FirebaseMessaging.getInstance().token.await()
        if (token.isNotEmpty) {
            getUsers().await()
        }
    } catch (e: Exception){
        // ...
    }
}

await function waits for task to complete.