A few interesting null-safety bugs which you might...

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[Sam]

A few interesting null-safety bugs which you might not know you can still run across in Kotlin: https://link.medium.com/crB736lsXxb

[CLOVIS]

That last one has bit me multiple times before in this shape:

abstract class Foo {
    abstract val name: String

    init {
        require(name.length < 20)
    }
}

class FooImpl(override val name: String) : Foo()

[CLOVIS]

I haven't had issues with the others, but this one I frequently have

[Stephan Schröder]

interesting stuff, I'm not happy that those null-unsafe niches exist 😑 but I haven't run into any of them yet.
I can see case 3 happening, but I'm more concerned about case 2. It's equally likely to cause a NullPointer as a ClassCastException:

val listOfLists = listOf(listOf(1))
    val values = listOfLists.filterIsInstance<List<String>>()
    println("Values: $values")
    println(values[0][0].uppercase())

leading to

Values: [[1]]
Exception in thread "main" java.lang.ClassCastException: class java.lang.Integer cannot be cast to class java.lang.String

type erasure at its finest.