Missing initialization in data/fewshot_pose_dataset.py

[GIMPS]

The latest commit on data preprocessing leads to UnboundLocalError during inference. ref_ppl_indices and ppl_indices should be initialized to None at data/fewshot_pose_dataset.py#L90. @tcwang0509 please kindly have a look.

[tcwang0509]

Thanks for pointing this out! It is fixed now.