Crash Missing key max_learner_queue_size

Run

python polyhydra.py actor_device=cpu

and the baseline crashes immediately with error:

Traceback (most recent call last):
Server listening on unix:/tmp/poly.outputs.2021-06-13.16-27-24.56
  File "/gpfsdswork/projects/rech/knb/uyr14tk/home/xtofNLE/neurips-2021-the-nethack-challenge/nethack_baselines/torchbeast/polyhydra.py", line 141, in main
    run_learner(lrn_flags)
  File "/gpfsdswork/projects/rech/knb/uyr14tk/home/xtofNLE/neurips-2021-the-nethack-challenge/nethack_baselines/torchbeast/polyhydra.py", line 77, in run_learner
    polybeast_learner.main(flags)
  File "/gpfsdswork/projects/rech/knb/uyr14tk/home/xtofNLE/neurips-2021-the-nethack-challenge/nethack_baselines/torchbeast/polybeast_learner.py", line 515, in main
    train(flags)
  File "/gpfsdswork/projects/rech/knb/uyr14tk/home/xtofNLE/neurips-2021-the-nethack-challenge/nethack_baselines/torchbeast/polybeast_learner.py", line 254, in train
    if flags.max_learner_queue_size is None:
omegaconf.errors.ConfigAttributeError: Missing key max_learner_queue_size
    full_key: max_learner_queue_size
    object_type=dict