An object that is stored in an array and later destroy()'d is not set to null, but is instead "corrupt"

import QtQuick 2.5
import QtQuick.Window 2.2
import QtQuick.Controls 2.0

Window {
    id: window
    visible: true
    width: 400
    height: 400

    property var obj
    property var collection: []

    Component.onCompleted:  {
        // create
        obj = Qt.createQmlObject("import QtQuick 2.0; Rectangle {}", this)
        collection[0] = Qt.createQmlObject("import QtQuick 2.0; Rectangle {}", this)
        // destroy
        obj.destroy()
        collection[0].destroy()
    }

    Timer {
        interval: 1000
        repeat: true
        running: true
        onTriggered: {
            console.log(obj, collection[0])
        }
    }
}