Nullable value causes NullPointerException

Support
1 
val a:Boolean? = false
// if I set break point here and set a = null,
// then resume program will show NullPointerException
1.run {
    a?.let { false }   // line 104
}.apply {
    println(a)
}

Exception in thread “main” java.lang.NullPointerException
at TestKt.main(Test.kt:104)
at TestKt.main(Test.kt)

What causes this NullPointerException?

2

Perhaps the compiler can see that the value cannot* be null at that point, and so treats the .? safe-call like a normal . call?

(* Cannot — except for ‘impossible’ situations like changing it in a debugger…)

By the way, it would be helpful if you could post the code as text, not an image.

3

Thanks for your reply!

In real project, the location of “1” and “a” are two function, they will return the same type value, so I need “?.” for null safety, but when “a” return null, the NullPointerException will happen