/set_lang's buttons do not work

[mhthies]

When clicking a language button of the /set_lang inline keyboard, the following exception is logged:

qaqa_bot.bot - ERROR - Error while update {'update_id': 570115936, 'callback_query': {'id': '356326171076547235', 'chat_instance': '<snip>', 'message': {'message_id': 19, 'date': 1588425785, 'chat': {'id': <snip>, 'type': 'private', 'username': '<snip>', 'first_name': '<snip>', 'last_name': '<snip>'}, 'text': 'Please choose:', 'entities': [], 'caption_entities': [], 'photo': [], 'new_chat_members': [], 'new_chat_photo': [], 'delete_chat_photo': False, 'group_chat_created': False, 'supergroup_chat_created': False, 'channel_chat_created': False, 'reply_markup': {'inline_keyboard': [[{'text': '🇩🇪', 'callback_data': 'de'}, {'text': '🇬🇧', 'callback_data': 'en'}]]}, 'from': {'id': 1223479557, 'first_name': 'QAQA-Test-Bot (Michael)', 'is_bot': True, 'username': 'qaqagame_michael_test_bot'}}, 'data': 'en', 'from': {'id': <snip>, 'first_name': '<snip>', 'is_bot': False, 'last_name': '<snip>', 'username': '<snip>', 'language_code': 'de'}}, '_effective_user': {'id': <snip>, 'first_name': '<snip>', 'is_bot': False, 'last_name': '<snip>', 'username': '<snip>', 'language_code': 'de'}, '_effective_chat': {'id': <snip>, 'type': 'private', 'username': '<snip>', 'first_name': '<snip>', 'last_name': '<snip>'}, '_effective_message': {'message_id': 19, 'date': 1588425785, 'chat': {'id': <snip>, 'type': 'private', 'username': '<snip>', 'first_name': '<snip>', 'last_name': '<snip>'}, 'text': 'Please choose:', 'entities': [], 'caption_entities': [], 'photo': [], 'new_chat_members': [], 'new_chat_photo': [], 'delete_chat_photo': False, 'group_chat_created': False, 'supergroup_chat_created': False, 'channel_chat_created': False, 'reply_markup': {'inline_keyboard': [[{'text': '🇩🇪', 'callback_data': 'de'}, {'text': '🇬🇧', 'callback_data': 'en'}]]}, 'from': {'id': 1223479557, 'first_name': 'QAQA-Test-Bot (Michael)', 'is_bot': True, 'username': 'qaqagame_michael_test_bot'}}}
Traceback (most recent call last):
  File "/home/michael/Documents/Freizeit/Programme/python/QAQAbot/venv/lib/python3.8/site-packages/telegram/ext/dispatcher.py", line 343, in process_update
    handler.handle_update(update, self, check, context)
  File "/home/michael/Documents/Freizeit/Programme/python/QAQAbot/venv/lib/python3.8/site-packages/telegram/ext/handler.py", line 117, in handle_update
    return self.callback(update, context)
  File "/home/michael/Documents/Freizeit/Programme/python/QAQAbot/qaqa_bot/bot.py", line 235, in button
    command = query.message.reply_to_message.text
AttributeError: 'NoneType' object has no attribute 'text'