Custom ToolBar for each Fragment of BottomNavigationBar with Kotlin

Android Studio generated simple template with following MainActivity code:

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)
        setupBottomNavigationBar()
    }

    private fun setupBottomNavigationBar() {
        val navView: BottomNavigationView = findViewById(R.id.bottom_nav_view)

        val navController = findNavController(R.id.nav_host_fragment)
        // Passing each menu ID as a set of Ids because each
        // menu should be considered as top level destinations.
        val appBarConfiguration = AppBarConfiguration(setOf(
            R.id.navigation_profile, R.id.navigation_chats,
            R.id.navigation_conferences, R.id.navigation_settings))
        setupActionBarWithNavController(navController, appBarConfiguration)
        navView.setupWithNavController(navController)
    }

And here's activity_main.xml:

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:id="@+id/container"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <com.google.android.material.bottomnavigation.BottomNavigationView
        android:id="@+id/bottom_nav_view"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_marginStart="0dp"
        android:layout_marginEnd="0dp"
        android:background="@color/colorPrimary"
        app:itemIconTint="@color/colorPrimaryDark"
        app:itemTextColor="@color/colorPrimaryDark"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toRightOf="parent"
        app:menu="@menu/bottom_nav_menu" />

    <fragment
        android:id="@+id/nav_host_fragment"
        android:name="androidx.navigation.fragment.NavHostFragment"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        app:defaultNavHost="true"
        app:layout_constraintBottom_toTopOf="@id/bottom_nav_view"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toRightOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        app:navGraph="@navigation/mobile_navigation" />

</androidx.constraintlayout.widget.ConstraintLayout>

But when I change AppTheme style parent to "Theme.AppCompat.Light.NoActionBar" the app crashes with following error:

java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.acase/com.example.acase.MainActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'void androidx.appcompat.app.ActionBar.setTitle(java.lang.CharSequence)' on a null object reference

It's trying to set title of fragment on nonexistent ActionBar.

So the question is how can I setup custom toolbar for each Fragment without showing default toolbar?