Dynamic generation of PieSeries from javascript cause warning "QList::insert(): Index out of range."

import QtQuick 2.15
import QtQuick.Window 2.15
import QtCharts 2.15
import QtQuick.Controls 2.15

Window {
    visible: true
    width: 640
    height: 480
    title: qsTr("Hello World")

    ListModel {
        id: exampleModel

        ListElement {
            label: "A"
            value: 2.45
        }
        ListElement {
            label: "B"
            value: 3.25
        }
        ListElement {
            label: "C"
            value: 1.95
        }
    }

    ChartView {
        anchors.fill: parent

        legend.alignment: Qt.AlignBottom
        antialiasing: true

        PieSeries {
            id: examplePieSeries
        }

        QtObject {
            property var model: exampleModel

            function refreshPieSeries() {
                examplePieSeries.clear()
                let modelLenght = model.count
                for (var i = 0; i < modelLenght; ++i) {
                    console.log("Before append " + i)
                    console.log("Label : " + model.get(i).label)
                    console.log("Value : " + model.get(i).value)
                    var pieslice = examplePieSeries.append(model.get(i).label,
                                                           model.get(i).value)
                    console.log("After append " + i)
                }
            }

            Component.onCompleted: {
                refreshPieSeries()
            }

            onModelChanged: {
                refreshPieSeries()
            }
        }
    }
}