easing.type on specific ColorAnimation/PropertyAnimation triggers ununderstandable error

import QtQuick 2.0
import QtQuick.Window 2.0

Window {
    visible: true
    width: 640
    height: 480
    id: root

    Rectangle {
        id: outLed
        width: height
        height: parent.height / 2
        radius: width / 2

        color: "darkgray"

        ColorAnimation on color {
            id: colorAnimOut
            from: "Red"
            to: "darkgray"
            duration: 250

            easing.type: Easing.InOutQuad
        }
    }
}