Notice: Trying to get property of non-object in _hs_nodereference_get_field_from_path()

I see lots of these errors in my database log:

Notice: Trying to get property of non-object in _hs_nodereference_get_field_from_path() (line 790 of sites/all/modules/hs_nodereference/hs_nodereference.module).

The attached patch fixes this.