corrupt cookies raise exception

[bkreider]

I'm not sure how i ended up with a null cookie, but it cased problems with min(). If the cookie length is 0, we should just ignore the file (or even better remove it). Or if raising an exception, raise AEFatalError and handle gracefully and ask the user to remove it.

Traceback (most recent call last):
  File "/opt/anaconda/envs/ae5-tools/bin/ae5", line 10, in <module>
    sys.exit(main())
  File "/opt/anaconda/envs/ae5-tools/lib/python3.7/site-packages/ae5_tools/cli/main.py", line 132, in main
    cli(obj={})
  File "/opt/anaconda/envs/ae5-tools/lib/python3.7/site-packages/click/core.py", line 764, in __call__
    return self.main(*args, **kwargs)
  File "/opt/anaconda/envs/ae5-tools/lib/python3.7/site-packages/click/core.py", line 717, in main
    rv = self.invoke(ctx)
  File "/opt/anaconda/envs/ae5-tools/lib/python3.7/site-packages/click/core.py", line 1137, in invoke
    return _process_result(sub_ctx.command.invoke(sub_ctx))
  File "/opt/anaconda/envs/ae5-tools/lib/python3.7/site-packages/click/core.py", line 1137, in invoke
    return _process_result(sub_ctx.command.invoke(sub_ctx))
  File "/opt/anaconda/envs/ae5-tools/lib/python3.7/site-packages/click/core.py", line 956, in invoke
    return ctx.invoke(self.callback, **ctx.params)
  File "/opt/anaconda/envs/ae5-tools/lib/python3.7/site-packages/click/core.py", line 555, in invoke
    return callback(*args, **kwargs)
  File "/opt/anaconda/envs/ae5-tools/lib/python3.7/site-packages/ae5_tools/cli/commands/account.py", line 23, in list
    records = config.list()
  File "/opt/anaconda/envs/ae5-tools/lib/python3.7/site-packages/ae5_tools/config.py", line 102, in list
    expires = min(cookie.expires for cookie in cookies)
ValueError: min() arg is an empty sequence