Why does PyQt5 QML crash when closing a child window?

Question

Python

In general, the child window opens, everything is fine, but when you click on the cross, Python crashes with this error QPixmap: Must construct a QGuiApplication before a QPixmap

def main():
    # Создаем экземпляр приложения
    app = QGuiApplication(sys.argv)
    # Создаем QML движок
    engine = QQmlApplicationEngine()
    # загружаем файл qml в движок
    path = os.path.abspath("C:/Users/fsociety/Desktop/pyprofiler/test/ui/login.qml")
    engine.load(path)

    if not engine.rootObjects():
        return -1

    return app.exec_()

if __name__ == "__main__":
    sys.exit(main())

Parent login.qml

import QtQuick 2.12
import QtQuick.Controls 2.12

ApplicationWindow {
    id: loginwindow
    visible: true
    minimumHeight: 640
    maximumHeight: 640

    minimumWidth: 1030
    maximumWidth: 1030

    title: "ProfilerApp"

    StackView {
        id: stackView
        anchors.fill: parent
    }

    Rectangle {
        id: root
        width: 430
        height: 467
        anchors.centerIn: parent

        Column {
            id: main
            width: root.width
            height: root.height
            spacing: 50

            Rectangle {
                id: welcome
                width: 311
                height: 61
                anchors.horizontalCenter: main.horizontalCenter

                Column {
                    id: column
                    width: welcome.width
                    height: welcome.height
                    spacing: 7

                    Rectangle {
                        width: 213
                        height: 33
                        anchors.horizontalCenter: column.horizontalCenter

                        Text {
                            text: "Войти в аккаунт"
                            font.family: "Roboto"
                            font.pixelSize: 28
                            color: "#202002"
                        }
                    }

                    Rectangle {
                        id: second_text
                        width: 311
                        height: 21

                        Text {
                            text: "Пожалуйста, войдите в аккаунт"
                            font.family: "Roboto"
                            font.pixelSize: 18
                            color: "#202002"
                            opacity: 0.5
                            anchors.centerIn: second_text
                        }
                    }

                }
            }

            Rectangle {
                id: rectangle
                width: 430
                height: 356

                Rectangle {
                    id: group
                    width: 340
                    height: 257
                    anchors.centerIn: rectangle

                    Column {
                        width: width.group
                        height: height.group
                        spacing: 15
                        
                        Rectangle {
                            id: login
                            width: 340
                            height: 56
                            border.color: "#DDDDDD"
                            border.width: 1
                            radius: 4

                            TextInput {
                                id: placeholder
                                maximumLength: 49
                                anchors.fill: login
                                anchors.margins: 18
                            }
                        }

                        Rectangle {
                            id: password
                            width: 340
                            height: 56
                            border.color: "#DDDDDD"
                            border.width: 1
                            radius: 4

                            TextInput {
                                maximumLength: 49
                                anchors.fill: password
                                anchors.margins: 18
                            }
                        }

                        Rectangle {
                            id: button
                            width: 340
                            height: 56

                            Button {
                                id: control
                                text: "Войти в аккаунт"
                                anchors.fill: button
                                font.family: "Roboto"
                                font.pixelSize: 14
                                
                                contentItem: Text {
                                    text: control.text
                                    font: control.font
                                    opacity: enabled ? 1.0 : 0.3
                                    color: control.down ? "#FA8072" : "#696969"
                                    horizontalAlignment: Text.AlignHCenter
                                    verticalAlignment: Text.AlignVCenter
                                    elide: Text.ElideRight
                                }

                                 background: Rectangle {
                                    implicitWidth: 90
                                    implicitHeight: 30
                                    opacity: enabled ? 1 : 0.3
                                    border.color: control.down ? "#FA8072" : "#696969"
                                    border.width: 1
                                    radius: 4

                                }
                            }
                        }

                        Rectangle {
                            id: text
                            y: 15
                            width: 340
                            height: 20

                            Button {
                                id: auth
                                text: "Зарегистрироваться"
                                anchors.fill: text
                                font.family: "Roboto"
                                font.pixelSize: 16

                                contentItem: Text {
                                    text: auth.text
                                    font: auth.font
                                    color: auth.down ? "#ADADAD" : "#696969"
                                    opacity: enabled ? 1 : 0.3
                                    horizontalAlignment: Text.AlignHCenter
                                    verticalAlignment: Text.AlignVCenter
                                    elide: Text.ElideRight
                                }

                                background: Rectangle {
                                    implicitWidth: 90
                                    implicitHeight: 30
                                    opacity: enabled ? 1 : 0.3            
                                }

                                onClicked: {
                                    stackView.push("registration.qml")
                                    loginwindow.close()
                                }
                            }

                        }

                    }

                }
            }
        }

    }

}



Это дочернее окно registration.qml

import QtQuick 2.12
import QtQuick.Controls 2.12

ApplicationWindow {
    id: registration
    visible: true
    minimumHeight: 640
    maximumHeight: 640

    minimumWidth: 1030
    maximumWidth: 1030

    title: "ProfilerApp"
}

Answer 1

Problem solved. Implemented through a signal, in registered.qml wrapped everything in Item instead of ApplicationWindow.