add instructions for unhandled exceptions in assert_close (#68722)
Summary: Pull Request resolved: https://github.com/pytorch/pytorch/pull/68722
Test Plan: Imported from OSS
Reviewed By: ngimel
Differential Revision: D32684446
Pulled By: mruberry
fbshipit-source-id: 04fe5730721d24e44692cdc9bb327484356ead3f
