Confusing error message when a model isn't supplied

[jxmorris12]

Output when I specify an attack without a model:

(torch) jxmorris12 12:50 PM > textattack attack --recipe bae
Traceback (most recent call last):
...
  File "/p/qdata/jm8wx/research/text_attacks/textattack/textattack/commands/attack/attack_args_helpers.py", line 343, in parse_model_from_args
    raise ValueError(f"Error: unsupported TextAttack model {args.model}")
ValueError: Error: unsupported TextAttack model None

I think that throwing an error (rather than providing a model by default) is the correct behavior. But this error message is unclear. We should check if any --model* args are supplied, and, if not, throw an error that says "please supply a model" or something like that!

[github-actions]

Stale issue message

[Hanyu-Liu-123]

I think the issue has been fixed so I'll close this issue!

[srujanjoshi]

As of the latest version of TextAttack, this issue is fixed.
This is the (more helpful) error that the code snippet now produces:
ValueError: Must supply pretrained model or dataset

Not sure why this is open again, but I will close it.