Error with readonly alias property

Hello,

here is a minimal example with which I get a segfault :

// main.qml

import QtQuick 2.14
import QtQuick.Window 2.14

Window {
    id: root

    readonly property alias initialWidth: root.privates.initialWidth
    readonly property alias initialHeight: root.privates.initialHeight

    readonly property QtObject privates: QtObject {

        property int initialWidth: 640
        property int initialHeight: 800
    }

    width: root.initialWidth
    height: root.initialHeight

    visible: true
    title: qsTr("Hello World")
}

In the main.qml, I'm just declaring two readonly alias properties in the purpose of exposing them outside outside of this component in a readonly manner. Yet I would like to allow the modifying of those properties inside this component via a private property, a non-existing concept in Qml but I try to mimic that with a property named "privates".

If I'm modifying this code in one of this way, everything work :

• Change "privates" from a property to a QtObject child of "root" with "privates" as id.
• Change the readonly properties "initialWidth" and "initialHeight" types from alias to int.

Is there something I'm doing wrong while using readonly aliases or is this an undefined bug/behavior ?

Thanks in advance.