import QtQuick
import QtQuick.Controls.Material

ApplicationWindow {
    id: window
    width: 640
    height: 480
    visible: true
    title: qsTr("Test")

    function onRequestDialog() {
        var dummy = "10";
        var cmp = Qt.createComponent("qrc:/main.qml");
        var dlg = cmp.createObject(window, {"helper": dummy});
    }
}

Error: main.qml:29:36: Could not compile function onRequestDialog: Cannot generate efficient code for DefineObjectLiteral
        var dlg = cmp.createObject(window, {"helper": dummy});
                                   ^^^^^^

Error: MWAppMainPage.qml:23:33: Could not compile function onRequestDialog: Instruction "generate_StoreLocal" not implemented
                dlg = component.createObject(appMainPage, {"helper": dialog});
                                ^^^^^^^^^^^^

Page {
    id: appMainPage
    function onRequestDialog(dialog : AbstractDialog) {
                var component, dlg;
                if (dialog.modal || !dialog.cancelable) {
                    component = Qt.createComponent("qrc:/imports/test/dialogs/MWAbstractDialog.qml");
                    dlg = component.createObject(appMainPage, {"helper": dialog});
                }
    }
}