Badge like notification (kotlin) : null object reference - kotlin

Question

I want to show some value in my ActionBar thanks to the "badge".
But, when I run my app, I have this error :
java.lang.NullPointerException: Attempt to invoke virtual method 'android.view.View android.view.View.findViewById(int)' on a null object reference
On this line :
notifCount = count.findViewById(R.id.notif_count)
Here's my code :
main.xml
<menu xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
>
<item
android:id="#+id/badge"
android:orderInCategory="100"
android:title="#string/alertes"
android:actionLayout="#layout/feed_update_count"
app:showAsAction="always" />
</menu>
feed_update.xml
<?xml version="1.0" encoding="utf-8"?>
<Button xmlns:android="http://schemas.android.com/apk/res/android"
android:id="#+id/notif_count"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:minWidth="32dp"
android:minHeight="32dp"
android:background="#drawable/red_circle"
android:text="0"
android:textSize="16sp"
android:textColor="#android:color/white"
android:gravity="center"
android:padding="2dp"
android:singleLine="true">
</Button>
main_activity.kt
private lateinit var notifCount: Button
var mNotifCount = 0
override fun onCreateOptionsMenu(menu: Menu): Boolean {
// Inflate the menu; this adds items to the action bar if it is present.
menuInflater.inflate(R.menu.main, menu)
val count = menu.findItem(R.id.badge).actionView
notifCount = count.findViewById(R.id.notif_count)
notifCount.text = "1"
return super.onCreateOptionsMenu(menu)
//return true
}

Answer 1

Count should be
val count = menu.findItem(R.id.badge)
notifCount = count.findViewById(R.id.notif_count)
notifCount.text = "1"

Answer 2

Got it :
change
android:actionLayout="#layout/feed_update_count"
to
app:actionLayout="#layout/feed_update_count"