Add more error checking in subclass creation (#64746)

Add more error checking in subclass creation (#64746)

Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/64746

This extracts the error checking that used to be in the PR above.
We are not going to land the proposed fix there, but I think we want this error checking in right now as these would lead to respectively a memory leak and arbitrary memory read/write.

Test Plan: Imported from OSS

Reviewed By: ngimel

Differential Revision: D30867569

Pulled By: albanD

fbshipit-source-id: bf468033fb8b49fcb26eed423f5fad82b4a46c56