Raise TypeError on assigned grad with wrong type (#64876)
Summary:
Fixes https://github.com/pytorch/pytorch/issues/64813
Raises a TypeError when assigned value to a grad is not a Tensor or
None.
Adds tests.
cc ezyang gchanan
Pull Request resolved: https://github.com/pytorch/pytorch/pull/64876
Reviewed By: anjali411
Differential Revision: D30901678
Pulled By: soulitzer
fbshipit-source-id: dbb3cb5fd0bbac6918e0b2e2f51d340daa43dee0
