Sublcassing Flask application doesn't run

Trying to run this simple Flask app, not creating a Flask app directly, but subclassing it instead:

#!/usr/bin/env python
# -*- coding: UTF-8 -*-

import logging

from flask import Flask


class TestFlaskApp(Flask):

    def __init__(self):

        super(Flask, self).__init__("PyPad")

        self._logger = logging.getLogger(self.__class__.__name__)

        self.debug = True

        self.route('/', defaults={'path': '.'})
        self.route('/<path:path>')
        def catch_all(path):
            return path

app = TestFlaskApp()
app.run()

Throws this error:

Traceback (most recent call last):
  File "/tmp/myproject/test.py", line 24, in <module>
    app = TestFlaskApp()
  File "/tmp/myproject/test.py", line 17, in __init__
    self.debug = True
  File "/usr/lib/python2.7/dist-packages/flask/config.py", line 36, in __set__
    obj.config[self.__name__] = value
AttributeError: 'TestFlaskApp' object has no attribute 'config'

Using:

• Ubuntu 16.04 LTS Xenial
• Python 2.7.11+
• Flask (0.10.1)