Segfault using QScxmlStateMachine.submitEvent(QScxmlEvent)

<?xml version="1.0" encoding="UTF-8"?>
<scxml xmlns="http://www.w3.org/2005/07/scxml" version="1.0" binding="early" name="demo.scxml">
    <transition type="internal" event="MY_EVENT"/>
    <state id="StateMachine"/>
</scxml>

#!/usr/bin/env python

import sys

from PySide2.QtCore import QObject, QCoreApplication, SLOT, Slot
from PySide2.QtScxml import QScxmlStateMachine, QScxmlEvent


class Backend(QObject):
    def __init__(self, machine):
        super(Backend, self).__init__()
        self.machine = machine
        self.machine.connectToState('StateMachine', self,
                                    SLOT('state_machine_active(bool)'))
        self.machine.connectToEvent('MY_EVENT', self, SLOT('my_event()'))

    @Slot(bool)
    def state_machine_active(self, active):
        print('StateMachine::active: %s' % active)
        #self.machine.submitEvent('MY_EVENT')
        ev = QScxmlEvent()
        ev.setName('MY_EVENT')
        ev.setEventType(QScxmlEvent.ExternalEvent)
        self.machine.submitEvent(ev)

    @Slot()
    def my_event(self, *args, **kwargs):
        print('MY_EVENT:', args, kwargs)


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

    machine = QScxmlStateMachine.fromFile('demo.scxml')
    b = Backend(machine)
    machine.start()

    sys.exit(app.exec_())