[SR][easy] Stack/concat out variants do not segfault on empty inputs (#73704)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/73704
Empty inputs are invalid for these ops. But while looking for optimizations, I noticed that these ops just segfault when that happens, which is not helpful for users. Added a check/error message.
ghstack-source-id: 150812721
Test Plan: New unit tests
Reviewed By: hlu1
Differential Revision: D34596954
fbshipit-source-id: 6b22a3a255273920210dcd41f54a9d238bbbcc14
(cherry picked from commit 9e950bfffef36c320638662bdb72f19eb805a228)
