Given a function emitError, as defined at https://github.com/krontech/chronos-gui-2/blob/be81cf2ae25e74d407d47f4eebe9a11f62524d71/src/coordinator_api.py#L751,
def emitError(self, message: str) -> None:
error = QDBusMessage.createError(QDBusError.Failed, message)
QDBusConnection.systemBus().send(error)