Error while issuing $trade

[DMcP89]

Describe the bug
calling $trade results in an error

To Reproduce
Steps to reproduce the behavior:

1. issue $trade command

Expected behavior
Latest trade awaiting league approval is displayed

Additional context

[2021-11-30 23:51:21,270 INFO] [/home/dave/workspace/python/bots/harambot/harambot/cogs/yahoo.py.yahoo.trade] trade called
Error while fetching latest trade
Traceback (most recent call last):
  File "/home/dave/workspace/python/bots/harambot/harambot/yahoo_api.py", line 159, in get_latest_trade
    return accepted_trades[0]
IndexError: list index out of range
Ignoring exception in command trade:
Traceback (most recent call last):
  File "/home/dave/workspace/python/bots/harambot/.venv/lib/python3.7/site-packages/discord/ext/commands/core.py", line 85, in wrapped
    ret = await coro(*args, **kwargs)
  File "/home/dave/workspace/python/bots/harambot/harambot/cogs/yahoo.py", line 26, in setup
    await func(cog, ctx)
  File "/home/dave/workspace/python/bots/harambot/harambot/cogs/yahoo.py", line 72, in trade
    trader = teams[latest_trade['trader_team_key']]
TypeError: 'NoneType' object is not subscriptable

The above exception was the direct cause of the following exception:

Traceback (most recent call last):
  File "/home/dave/workspace/python/bots/harambot/.venv/lib/python3.7/site-packages/discord/ext/commands/bot.py", line 939, in invoke
    await ctx.command.invoke(ctx)
  File "/home/dave/workspace/python/bots/harambot/.venv/lib/python3.7/site-packages/discord/ext/commands/core.py", line 863, in invoke
    await injected(*ctx.args, **ctx.kwargs)
  File "/home/dave/workspace/python/bots/harambot/.venv/lib/python3.7/site-packages/discord/ext/commands/core.py", line 94, in wrapped
    raise CommandInvokeError(exc) from exc
discord.ext.commands.errors.CommandInvokeError: Command raised an exception: TypeError: 'NoneType' object is not subscriptable