Swimbot Error

Traceback (most recent call last):
  File "C:\Users\wmiller\AppData\Local\Programs\Python\Python39\lib\site-packages\discord\ext\commands\core.py", line 85, in wrapped
    ret = await coro(*args, **kwargs)
  File "c:\Users\wmiller\Desktop\Swimbot\whois.py", line 574, in seen
    await ctx.send(f'I last saw **{ctx.message.mentions[0].name}** playing **{name_list[index]}** {round(time_delta_min)} minutes ago.')
IndexError: list index out of range