View does not have a NavController set

Question

My app has a bottom nav. bar. I am using koin for dependency injection. Fragment3, which is the fragment I am starting from, is part of a nested navigation graph, in which the viewmodel is scoped to. When I navigate from Fragment3 to another fragment, through the bottom nav. bar, and then back to Fragment3, I get the following error. Any help?

class MainActivity : AppCompatActivity(), BottomNavBarVisibilityController {

lateinit var binding: ActivityMainBinding

override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)

    binding = ActivityMainBinding.inflate(layoutInflater)
    setContentView(binding.root)

    setupBottomNav()
}

override fun showBottomNavBar() {
    binding.bottomNavBar.visibility = View.VISIBLE
}

override fun hideBottomNavBar() {
    binding.bottomNavBar.visibility = View.GONE
}

private fun setupBottomNav() {
    binding.bottomNavBar.selectedItemId = R.id.fragment3

    binding.bottomNavBar.setOnItemSelectedListener {

        when(it.itemId) {
            R.id.fragment1 -> setupFragment(Fragment1())
            R.id.fragment2 -> setupFragment(Fragment2())
            R.id.fragment3 -> setupFragment(Fragment3())
            R.id.fragment4 -> setupFragment(Fragment4())
            R.id.fragment5 -> setupFragment(Fragment5())
            else -> false
        }
    }
}

private fun setupFragment(fragment: Fragment): Boolean {
    val transaction = supportFragmentManager.beginTransaction()
    transaction.replace(R.id.nav_host_fragment_container, fragment)
    transaction.commit()
    return true
}
}



class Fragment3 : Fragment() {

private var _binding: Fragment3Binding? = null
private val binding get() = _binding!!

private val viewModel: Fragment3FlowViewModel by koinNavGraphViewModel(R.id.fragment_3_nav_graph)

override fun onCreateView(
    inflater: LayoutInflater, container: ViewGroup?,
    savedInstanceState: Bundle?
): View? {
    _binding = Fragment3Binding.inflate(layoutInflater)
    return binding.root
}



val appModule = module {

...

viewModel {
    Fragment3FlowViewModel()
}

}

FATAL EXCEPTION: main Process: com.example.coursecpm, PID: 16554 java.lang.IllegalStateException: View androidx.constraintlayout.widget.ConstraintLayout{7ff29b6 V.E...... ......ID 0,0-0,0} does not have a NavController set at androidx.navigation.Navigation.findNavController(Navigation.kt:71) at androidx.navigation.fragment.NavHostFragment$Companion.findNavController(NavHostFragment.kt:364) at androidx.navigation.fragment.FragmentKt.findNavController(Fragment.kt:29) at com.example.coursecpm.presentation.bottomnav.purchase.PurchaseFragment$special$$inlined$koinNavGraphViewModel$default$1.invoke(NavGraphExt.kt:23) at com.example.coursecpm.presentation.bottomnav.purchase.PurchaseFragment$special$$inlined$koinNavGraphViewModel$default$1.invoke(NavGraphExt.kt:23) at com.example.coursecpm.presentation.bottomnav.purchase.PurchaseFragment$special$$inlined$koinNavGraphViewModel$default$2.invoke(FragmentVM.kt:78) at com.example.coursecpm.presentation.bottomnav.purchase.PurchaseFragment$special$$inlined$koinNavGraphViewModel$default$2.invoke(FragmentVM.kt:49) at kotlin.UnsafeLazyImpl.getValue(Lazy.kt:81) at com.example.coursecpm.presentation.bottomnav.purchase.PurchaseFragment.getViewModel(PurchaseFragment.kt:21) at com.example.coursecpm.presentation.bottomnav.purchase.PurchaseFragment$setupObservers$1.invokeSuspend(PurchaseFragment.kt:46) at kotlin.coroutines.jvm.internal.BaseContinuationImpl.resumeWith(ContinuationImpl.kt:33) at kotlinx.coroutines.internal.DispatchedContinuationKt.resumeCancellableWith(DispatchedContinuation.kt:367) at kotlinx.coroutines.intrinsics.CancellableKt.startCoroutineCancellable(Cancellable.kt:30) at kotlinx.coroutines.intrinsics.CancellableKt.startCoroutineCancellable$default(Cancellable.kt:25) at kotlinx.coroutines.CoroutineStart.invoke(CoroutineStart.kt:110) at kotlinx.coroutines.AbstractCoroutine.start(AbstractCoroutine.kt:126) at kotlinx.coroutines.BuildersKt__Builders_commonKt.launch(Builders.common.kt:56) at kotlinx.coroutines.BuildersKt.launch(Unknown Source:1) at kotlinx.coroutines.BuildersKt__Builders_commonKt.launch$default(Builders.common.kt:47) at kotlinx.coroutines.BuildersKt.launch$default(Unknown Source:1) at com.example.coursecpm.presentation.bottomnav.purchase.PurchaseFragment.setupObservers(PurchaseFragment.kt:44) at com.example.coursecpm.presentation.bottomnav.purchase.PurchaseFragment.onViewCreated(PurchaseFragment.kt:34) at androidx.fragment.app.Fragment.performViewCreated(Fragment.java:3147) at androidx.fragment.app.FragmentStateManager.createView(FragmentStateManager.java:588) at androidx.fragment.app.FragmentStateManager.moveToExpectedState(FragmentStateManager.java:272) at androidx.fragment.app.FragmentManager.executeOpsTogether(FragmentManager.java:1943) at androidx.fragment.app.FragmentManager.removeRedundantOperationsAndExecute(FragmentManager.java:1839) at androidx.fragment.app.FragmentManager.execPendingActions(FragmentManager.java:1782) at androidx.fragment.app.FragmentManager$5.run(FragmentManager.java:565) at android.os.Handler.handleCallback(Handler.java:790) at android.os.Handler.dispatchMessage(Handler.java:99) at android.os.Looper.loop(Looper.java:164)