[fix] handle empty args in chain_matmul (#43553)
Summary:
Fixes https://github.com/pytorch/pytorch/issues/41817
Pull Request resolved: https://github.com/pytorch/pytorch/pull/43553
Reviewed By: agolynski
Differential Revision: D23342586
Pulled By: mruberry
fbshipit-source-id: c6349f8fa9fcefcf03681d92c085a21265d1e690
