I'm trying to add a "+" tab in a tabpane to create more tabs. Everything else is working fine, but calling

close()

from the tab itself throws a NPE. Minimal example:

class addTab : View(" + ") {
    override val root = label("You should not see this.")

    override fun onTabSelected() {
        super.onTabSelected()
        with(MainView.tabs) {
            tab("new", nonuniqueTab("foo"))
            tabs[tabs.size - 1].select()
        }
        close()
    }
}

creates a new tab from fragment just fine, tabs is the tabpane, but close causes

java.lang.NullPointerException: Cannot invoke "javafx.beans.value.ChangeListener.changed(javafx.beans.value.ObservableValue, Object, Object)" because "<local3>[<local7>]" is null

Or is it possible to reorder or open a tab between existing tabs to avoid having to close and reopen the + tab?