qmlls fails to provide auto-completion for formal parameters in signal handlers

import QtQuick
import QtQuick.Controls.Basic

Window {
    id: root
    width: 800
    height: 600
    visible: true
    color: combo.currentText

    ComboBox {
        id: combo
        model: ["red", "green", "blue"]
    }

    Component.onCompleted: console.log(root.color)
    onColorChanged: (col) => console.log(col)
}