Is there way to avoid initialisation crash?

abstract class A {
	
	init {
		foo()
	}

	abstract fun foo()
}

class B : A {
	val b = /* init b */

	override fun foo() {
		b.something() // crash
	}
}

The super class call

foo()

on init so, the property

b

is not yet initialised

You could call

foo()

later one way or another, or implement

foo()

through composition instead of inheritance, or somehow pass the information you're trying to convey with

foo()

implementation through the super constructor, etc.