Unused exception variables (#50181)
Summary:
These unused variables were identified by [pyflakes](https://pypi.org/project/pyflakes/). They can be safely removed to simplify the code.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/50181
Reviewed By: gchanan
Differential Revision: D25844270
fbshipit-source-id: 0e648ffe8c6db6daf56788a13ba89806923cbb76
