Add more verbose error message about PackedSequence lengths argument (#42891)
Summary:
Add given tensor dimentionality, device and dtype to the error message
Pull Request resolved: https://github.com/pytorch/pytorch/pull/42891
Reviewed By: ezyang
Differential Revision: D23068769
Pulled By: malfet
fbshipit-source-id: e49d0a5d0c10918795c1770b4f4e02494d799c51
