Kotlin app that creates illegal class names failing the test in Class.getSimpleName()

kotlinillegalclassname.kt

package sample

import javafx.application.Application
import javafx.collections.FXCollections
import javafx.scene.Scene
import javafx.scene.control.ListCell
import javafx.scene.control.ListView
import javafx.stage.Stage
import javafx.util.Callback

class Main : Application() {
    override fun start(stage: Stage) {
        val root = ListView<String>().apply {
            items = FXCollections.observableArrayList("One", "Two", "Three")
            cellFormat {
                // This line crashes with java.lang.InternalError: Malformed class name
                // at java.lang.Class.getSimpleName(Class.java:1330)
                println(javaClass.simpleName)
                text = item
            }
        }
        stage.scene = Scene(root)
        stage.show()
    }

    companion object {
        fun main(args: Array<String>) {
            Application.launch(*args)
        }
    }
}

// This is a convenience function that provides a cellfactory to a ListView, taken from the TornadoFX framework
// Changing 'crossinline' to 'noinline' seems to solve the problem
inline fun <T> ListView<T>.cellFormat(crossinline formatter: (ListCell<T>.(T) -> Unit)) {
    cellFactory = Callback {
        object : ListCell<T>() {
            override fun updateItem(item: T, empty: Boolean) {
                super.updateItem(item, empty)

                if (item == null || empty) {
                    text = null
                    graphic = null
                } else {
                    formatter(this, item)
                }
            }
        }
    }
}