Cannot Close Spyder with PyQt5

Question

I need your help!

I built a GUI with PyQt5 and my IDE is Spyder!

When I run PyQt in Spyder I cannot close it. What's the problem?

Also when I run it a second time, the menubar disappears...

import sys
from PyQt5 import QtWidgets
from PyQt5.QtWidgets import QApplication, QMainWindow
from mainwindow import Ui_MainWindow



class MainWindow(QMainWindow, Ui_MainWindow):
    def __init__(self):
        super().__init__()
        self.setupUi(self)
        
if __name__ == '__main__':
    app = QApplication(sys.argv)
    window = MainWindow()
    window.show()
    sys.exit(app.exec_())