Improve sugared value's error message (#42889)
Summary:
Stack from [ghstack](https://github.com/ezyang/ghstack):
* **https://github.com/pytorch/pytorch/issues/42889 Improve sugared value's error message**
I think most (if not all) cases where this code path is reached can be attributed to closing over a global variable.
Improving error message to make this clearer to users.
close https://github.com/pytorch/pytorch/issues/41288
Pull Request resolved: https://github.com/pytorch/pytorch/pull/42889
Reviewed By: SplitInfinity
Differential Revision: D23779347
Pulled By: gmagogsfm
fbshipit-source-id: ced702a96234040f79eb16ad998d202e360d6654
