This minimal example crashs on windows

import sys
import gi

gi.require_version('Gtk', '3.0')
from gi.repository import Gio
from gi.repository import Gtk


class App(Gtk.Application):
    def __init__(self):
        Gtk.Application.__init__(self,
                                 application_id="org.gnome.example",
                                 flags=Gio.ApplicationFlags.FLAGS_NONE)

    def do_activate(self):
        window = Gtk.ApplicationWindow(application=self)
        grid = Gtk.Grid()
        button = Gtk.Button('Notify')
        button.connect('clicked', self.on_button_clicked)
        grid.add(button)
        window.add(grid)
        window.show_all()

    def on_button_clicked(self, *args):
       notif = Gio.Notification.new('TESTMESSAGE')
       notif.set_body('TEST')
       self.send_notification('new_message', notif)


if __name__ == '__main__':
    app = App()
    app.run(sys.argv)



apptest2.py:27: Warning: g_object_new: assertion 'G_TYPE_IS_OBJECT (object_type)' failed
  self.send_notification('new_message', notif)