Include hierarchy information in C++ API loading error messages (#28499)
Summary:
Before, we would only give the key we are looking for (i.e. typically
just "No such serialized tensor 'weight'", no matter for which submodule
we were looking for a weight.
Now we error with "No such serialized tensor '0.conv1.weight'" or
similar.
The analogous information is added to missing module error messages.
I threw in a test, and it saved me already...
Pull Request resolved: https://github.com/pytorch/pytorch/pull/28499
Differential Revision: D18122442
Pulled By: yf225
fbshipit-source-id: a134b6d06ca33de984a11d6fea923244bcd9fb95
