Crashes when setting a QQmlListProperty

output

$ pip install PyQt5==5.7.1
$ python app.py
TypeError: list element must be of type 'str', not 'NoneType'
fish: “python app.py” terminated by signal SIGABRT (Abort)
$

setter_QQmlListProperty.py

import sys

from PyQt5 import QtCore, QtQml
from PyQt5.QtWidgets import QApplication


class CustomType(QtCore.QObject):
    def __init__(self, parent = None):
        super().__init__(parent)

        self._names = []

    @QtCore.pyqtProperty(QtQml.QQmlListProperty)
    def names(self):
        return QtQml.QQmlListProperty(str, self, self._names)
    @names.setter
    def names(self, names):
        print('Never see this')
        self._names = names

QML = b"""
import QtQuick.Controls 1.4

import CustomType 1.0

ApplicationWindow {
    visible: true
    width: 800
    height: 600

    CustomType {
      id: customType
      names: ["one", "two"]
      //names: [] // doesn't crash
    }
}
"""

app = QApplication(sys.argv)
QtQml.qmlRegisterType(CustomType, 'CustomType', 1, 0, 'CustomType')
engine = QtQml.QQmlApplicationEngine()
engine.loadData(QML)
app.exec_()