Telethon: resolve_bot_file_id returns None for valid file_id

Checklist

• The error is in the library’s code, and not in my own.
• I have searched for this issue before posting it and there isn’t a duplicate.
• I ran pip install -U https://github.com/LonamiWebs/Telethon/archive/master.zip and triggered the bug in the latest version.

Code that causes the issue

import asyncio

from telegram.ext import Updater, MessageHandler, Filters
from telethon.utils import resolve_bot_file_id, get_input_location
from telethon import TelegramClient

import logging

logging.basicConfig()

api_id = 123
api_hash = 'my_api_hash'
token = 'my_bot_token'


def file_handler(update, context):
    file = update.effective_message.document
    file_size = file.file_size
    file_id = file.file_id
    file_name = file.file_name
    if file_size > 20000000:
        loop = asyncio.new_event_loop()
        asyncio.set_event_loop(loop)
        get_file_telethon(file_id, file_name, loop)
    else:
        update.effective_message.document.get_file().download()


def get_file_telethon(file_id, file_name, loop):
    bot = TelegramClient('bot', api_id, api_hash, loop=loop).start(bot_token=token)
    with bot:
        document = resolve_bot_file_id(file_id)
        location = get_input_location(document)
        loop.run_until_complete(bot.download_file(location[1], file_name))


updater = Updater(token, use_context=True)
dp = updater.dispatcher
dp.add_handler(MessageHandler(Filters.document, file_handler))
updater.start_polling()
updater.idle()

...

Traceback

ERROR:telegram.ext.dispatcher:No error handlers are registered, logging exception.
Traceback (most recent call last):
  File "**/venv/lib/python3.6/site-packages/telethon/utils.py", line 768, in _get_file_info
    if location.SUBCLASS_OF_ID == 0x1523d462:
AttributeError: 'NoneType' object has no attribute 'SUBCLASS_OF_ID'

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "**/venv/lib/python3.6/site-packages/telegram/ext/dispatcher.py", line 425, in process_update
    handler.handle_update(update, self, check, context)
  File "**/venv/lib/python3.6/site-packages/telegram/ext/handler.py", line 145, in handle_update
    return self.callback(update, context)
  File **/bot.py", line 24, in file_handler
    get_file_telethon(file_id, file_name, loop)
  File "**/bot.py", line 33, in get_file_telethon
    location = get_input_location(document)
  File "**/venv/lib/python3.6/site-packages/telethon/utils.py", line 762, in get_input_location
    info = _get_file_info(location)
  File "**/venv/lib/python3.6/site-packages/telethon/utils.py", line 771, in _get_file_info
    _raise_cast_fail(location, 'InputFileLocation')
  File "**/venv/lib/python3.6/site-packages/telethon/utils.py", line 139, in _raise_cast_fail
    type(entity).__name__, target))
TypeError: Cannot cast NoneType to any kind of InputFileLocation.