Encountered an error while writing a command in QMessageBox. Who can advise?

Question

PyQt

I ran into a problem when adding a button to a QMessageBox
Here I will attach the code: (I marked the places of errors with #)

The code

# Form implementation generated from reading ui file 'untitled.ui'
#
# Created by: PyQt6 UI code generator 6.0.0
#
# WARNING: Any manual changes made to this file will be lost when pyuic6 is
# run again.  Do not edit this file unless you know what you are doing.


from PyQt6 import QtCore, QtGui, QtWidgets



class Ui_MainWindow(object):
    def setupUi(self, MainWindow):
        MainWindow.setObjectName("MainWindow")
        MainWindow.resize(247, 178)
        self.centralwidget = QtWidgets.QWidget(MainWindow)
        self.centralwidget.setObjectName("centralwidget")
        self.label = QtWidgets.QLabel(self.centralwidget)
        self.label.setGeometry(QtCore.QRect(20, 20, 47, 13))
        self.label.setObjectName("label")
        self.label_2 = QtWidgets.QLabel(self.centralwidget)
        self.label_2.setGeometry(QtCore.QRect(20, 50, 47, 13))
        self.label_2.setObjectName("label_2")
        self.lineEdit = QtWidgets.QLineEdit(self.centralwidget)
        self.lineEdit.setGeometry(QtCore.QRect(80, 10, 113, 20))
        self.lineEdit.setObjectName("lineEdit")
        self.lineEdit_2 = QtWidgets.QLineEdit(self.centralwidget)
        self.lineEdit_2.setGeometry(QtCore.QRect(80, 50, 113, 20))
        self.lineEdit_2.setObjectName("lineEdit_2")
        self.pushButton = QtWidgets.QPushButton(self.centralwidget)
        self.pushButton.setGeometry(QtCore.QRect(80, 100, 101, 21))
        self.pushButton.setObjectName("pushButton")
        MainWindow.setCentralWidget(self.centralwidget)
        self.menubar = QtWidgets.QMenuBar(MainWindow)
        self.menubar.setGeometry(QtCore.QRect(0, 0, 247, 21))
        self.menubar.setObjectName("menubar")
        MainWindow.setMenuBar(self.menubar)
        self.statusbar = QtWidgets.QStatusBar(MainWindow)
        self.statusbar.setObjectName("statusbar")
        MainWindow.setStatusBar(self.statusbar)

        self.retranslateUi(MainWindow)
        QtCore.QMetaObject.connectSlotsByName(MainWindow)
        self.lineEdit.textChanged.connect(self.ChangeText)
        self.lineEdit_2.textChanged.connect(self.ChangeText)
        self.pushButton.clicked.connect(self.Result)

    def Result (self):
        try:
            a=int(self.lineEdit.text())
            if a>300:
                a=a*0.1
            b=int(self.lineEdit_2.text())
            s=a*b
            msg=QtWidgets.QMessageBox()
            msg.setWindowTitle ('Идет подсчет...')
            msg.setText('Вы сотрудник нашей фирмы?')
            #Код перестает работать при добавлении нижней строки, не могу понять в чем проблема
            #msg.setStandardButtons(QMessageBox.Yes | QMessageBox.No)
            msg.exec()
        except:
            msg= QtWidgets.QMessageBox()
            msg.setWindowTitle ('Ошибка ввода!')
            msg.setText('Ошибка ввода данных!')
            if self.lineEdit.text()=='' or self.lineEdit_2.text ()== '':
                msg.setInformativeText('Введите исходные данные.')
            #Здесь такая же история
            #msg.setIcon (QMessageBox.Warning)
            msg.exec()
    
        
    def ChangeText (self):
        s = QtCore.QCoreApplication.instance().sender().text ()
        for i in range(len (s) -1, -1, -1):
            if not s[i].isdigit():
                s=s[0:i] + s[i +1:len(s)]
                break
        QtCore.QCoreApplication.instance ().sender().setText(s)

    def retranslateUi(self, MainWindow):
        _translate = QtCore.QCoreApplication.translate
        MainWindow.setWindowTitle(_translate("MainWindow", "MainWindow"))
        self.label.setText(_translate("MainWindow", "Цена"))
        self.label_2.setText(_translate("MainWindow", "Кол-во"))
        self.pushButton.setText(_translate("MainWindow", "Стоймость"))


if __name__ == "__main__":
    import sys
    app = QtWidgets.QApplication(sys.argv)
    MainWindow = QtWidgets.QMainWindow()
    ui = Ui_MainWindow()
    ui.setupUi(MainWindow)
    MainWindow.show()
    sys.exit(app.exec())

if __name__ == "__main__":
    import sys
    app = QtWidgets.QApplication(sys.argv)
    MainWindow = QtWidgets.QMainWindow()
    ui = Ui_MainWindow1()
    ui.setupUi(MainWindow)
    MainWindow.show()
    sys.exit(app.exec())