in this example, if I remove the `val callback = c...

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[Brian Donovan]

in this example, if I remove the val callback = callback line it no longer compiles, complaining that "reference has a nullable type". however, I would have expected that kotlin could properly smart cast callback to a non-optional inside the null check conditional. weirdly, changing callback() to callback.invoke() also makes it compile. this seems like a bug, or is () different from .invoke() on function types?

class Thing(
    private val callback: (() -> Unit)?
) {
    fun doSomething() {
        val callback = callback
        if (callback != null) {
            callback()
        }
    }
}

Thing { println("Hi!") }.doSomething()