[SR][easy] Fix FuseListUnpack 0-use corner case (#67165)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/67165
We previously skipped the optimization if `value_out->uses().size() > 1`. But it's possible that the number of uses is 0. In that case, it's not safe to access `value_out->uses()[0]`.
This is not causing any problems in production right now since we don't have any dead code before running this pass. But we should handle this case correctly to make the pass more robust.
Test Plan: CI
Reviewed By: hlu1
Differential Revision: D31887416
fbshipit-source-id: d30a5824e8bd1cda1debdc16524db3fb0da312f9
