ONNX Error Message on Missing Op (#33593)
Summary:
Print a complete and comprehensive error message with a description of the issue when an op is missing during ONNX export (previously an ambiguous "key not in registry" error was thrown which was not helpful for the user to understand the failure).
Pull Request resolved: https://github.com/pytorch/pytorch/pull/33593
Reviewed By: hl475
Differential Revision: D20052213
Pulled By: houseroad
fbshipit-source-id: ae3010a97efdab26effad5e4a418e9cc41f5b04e
