Improve error checking of Storage._writeFile. (#46036)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/46036
Previously, this function didn't do error-bounds checking on the GetItem (GET_ITEM) calls, which led to issues like https://github.com/pytorch/pytorch/issues/46020.
A better solution would be to use pybind, but given writing the file is going to dominate bounds checking, this is strictly better.
Test Plan: Imported from OSS
Reviewed By: mruberry
Differential Revision: D24228370
Pulled By: gchanan
fbshipit-source-id: f5d0a3d21ff12b4380beefe1e9954fa81ea2f567
