improve recursive scripting error message (#21841)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/21841
ghimport-source-id: fbca813d12ca4bfad7967e12c8dafe5eaba77cab
Test Plan: Imported from OSS
Reviewed By: zdevito
Differential Revision: D15857569
Pulled By: suo
fbshipit-source-id: 152eba10565cf7119508079e98512f116eb3a5a8
