[code robustness request] catch invalid batch_size

[xins981]

https://github.com/lianghongzhuo/PointNetGPD/blob/336eb9e9cbb534dea36b3e92e0d1b7adef13d7f3/PointNetGPD/main_1v.py#L49C6-L49C6

Hi, Hongzhuo. above code have the chance filter all batch data, which will make batchnorm layer throw an erroe( valid batch_size <= 1).
besides increase the batchsize to decrease null valid bath probability. beside that, have you more elegant means to catch this case and skip this iteration?