[jit] better error message (#43093)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/43093
without this it's hard to tell which module is going wrong
Test Plan:
```
> TypeError:
> 'numpy.int64' object in attribute 'Linear.in_features' is not a valid constant.
> Valid constants are:
> 1. a nn.ModuleList
> 2. a value of type {bool, float, int, str, NoneType, torch.device, torch.layout, torch.dtype}
> 3. a list or tuple of (2)
```
Reviewed By: eellison
Differential Revision: D23148516
fbshipit-source-id: b86296cdeb7b47c9fd69b5cfa479914c58ef02e6
