Compilation failed in Kotlin due to ? operator

I'm trying to understand the following scenario.

inline fun Any?.what(ifNotNull: (Any) -> Unit, ifNull: () -> Unit) {
    if (this == null) {
        ifNull()
    } else {
        ifNotNull(this)
    }
}

@OptIn(ExperimentalContracts::class)
@JvmSynthetic
inline fun <T> T?.whatIfNull(
    whatIfNot: (T) -> Unit,
    whatIf: () -> Unit,
) {
    contract {
        callsInPlace(whatIf, InvocationKind.AT_MOST_ONCE)
        callsInPlace(whatIfNot, InvocationKind.AT_MOST_ONCE)
    }
    if (this != null) {
        whatIfNot(this)
    } else {
        whatIf()
    }
}

fun main() {
    null?.what(
        ifNull = {
            println("It Works!")
        },
        ifNotNull = {
            println("It not working!!")
        },
    )
    null?.whatIfNull(
        whatIf = {
            println("It Works!")
        },
        whatIfNot = {
            println("It not working!!")
        },
    )
}

I got something like this for main when I compiled this code.

   public static final void main() {   }

When I remove the ? operator after null, like null.whatIfNull( will get

public static final void main() {
      Object $this$whatIfNull$iv = null;
      int $i$f$whatIfNull = false;
      int var2 = false;
      String var3 = "It Works!";
      System.out.println(var3);
   }

Im trying to understand this too. seems like it only compiled after removing the ?.

What could be the reason for this issue? Are there any specific blogs or articles? Please post as a comment, or kindly explain me. Thank you.!

The thing is when you write null?.<anythinghere> it already knows that <anythinghere> is unreachable so it just leaves it out. You might think that null? is a value of Any? but it is not. So it does not match. Consider this code:

fun main() {
    val a = null
    println(a?.test())
    println(a.test())
}

fun Any?.test() : String {
    return "Test"
}

Output will be:

null
Test

When writing null? you have an example of the first case, meaning it won't ever execute whatever is after it.