title: PyQt: No error msg (traceback) on exit
body: <p>My PyQt application no longer prints the error (stderr?) to the console.</p>
  
  <p>I use QtDesigner and import the UI like this:</p>
  
  <pre><code>from PyQt5 import QtCore, QtGui, QtWidgets
  import sys
  from PyQt5.uic import loadUiType
  Ui_MainWindow, QMainWindow = loadUiType("test.ui")
  
  class Main(QMainWindow, Ui_MainWindow):
      """Main window"""
      def __init__(self,parent=None):
          super(Main, self).__init__(parent)
          self.setupUi(self)
          self.pushButton.clicked.connect(self.testfunc)
  
     def testfunc(self):
          print(9/0)
  
  if __name__ == '__main__':
      app = QtWidgets.QApplication(sys.argv)
      main = Main()
      main.show()
      sys.exit(app.exec_())
  </code></pre>
  
  <p>test.ui contains a QPushButton and a label. When I call testfunc (which obviously gives an error) in a non-Qt application, I get the error message, traceback, etc. When I execute this code, it just exits. </p>
  
  <p>I wrote a PyQt application without QtDesigner before and it printed the errors to the console as expected. What's the difference with QtDesigner and inheritance?</p>