PSNR ValueError: math domain error

[NEFUJoeyChen]

https://github.com/megvii-research/ECCV2022-RIFE/blob/9e10b63db3e93c3ba02283260cee1f3a698c4b14/train.py#L113

Hello, when GT and PRED are too similar (mse<1e-10), an error will be reported, because too small MSE will lead to PSNR approaching infinity. It would be better to add an 'if' condition here. Usually, people do this when calculating PSNR.