Conflated channel crashes

gistfile1.txt

package com.example.launchwhendemo.ui.main

import android.os.Bundle
import android.util.Log
import android.view.View
import android.widget.Button
import androidx.fragment.app.Fragment
import androidx.lifecycle.ViewModel
import androidx.lifecycle.ViewModelProvider
import androidx.lifecycle.viewModelScope
import androidx.navigation.fragment.findNavController
import com.example.launchwhendemo.R
import kotlinx.coroutines.channels.Channel
import kotlinx.coroutines.delay
import kotlinx.coroutines.flow.onEach
import kotlinx.coroutines.flow.receiveAsFlow
import kotlinx.coroutines.launch
import observeIn

class MainFragment : Fragment(R.layout.main_fragment) {
    private lateinit var viewModel: MainViewModel

    override fun onViewCreated(
        view: View,
        savedInstanceState: Bundle?
    ) {
        super.onViewCreated(view, savedInstanceState)
        viewModel = ViewModelProvider(this).get(MainViewModel::class.java)

        view.findViewById<Button>(R.id.goButton).setOnClickListener { viewModel.go() }

        viewModel.events
                .onEach {
                    when(it) {
                        is MainViewModel.Event.A -> {
                            delay(500L) // for random reasons
                            val directions = MainFragmentDirections.actionMainFragmentToAFragment()
                            findNavController().navigate(directions)
                        }
                        MainViewModel.Event.B -> {
                            val directions = MainFragmentDirections.actionMainFragmentToBFragment()
                            findNavController().navigate(directions)
                        }
                    }
                }
                .observeIn(viewLifecycleOwner)
    }
}

class MainViewModel : ViewModel() {

    sealed class Event {
        object A: Event()
        object B: Event()
    }

    private val _eventChannel = Channel<Event>(Channel.CONFLATED)
    val events = _eventChannel.receiveAsFlow()

    fun go() {
        // Simulate two navigation events being sent more or less simultaneously,
        // one as a response to user action and another as a response to something else, say a slow web service
        viewModelScope.launch {
            _eventChannel.send(Event.A)
        }

        viewModelScope.launch {
            _eventChannel.send(Event.B)
        }
    }
}

class AFragment : Fragment(R.layout.fragment_a) {}
class BFragment : Fragment(R.layout.fragment_b) {}