Throw exception from future methods returning void
Throw exception from future methods returning void

Summary:
We were not generating the right code. In the callback of the future
method, we need to check if an exception exists and throw it.

Test Plan: Where are the unit tests for this?

Reviewed By: davejwatson@fb.com

Subscribers: ruibalp, fugalh, alandau

FB internal diff: D1505251

Tasks: 4939669

SergeyMakarenko/fbthrift,uber/fbthrift,soumith/fbthrift,guker/fbthrift,SergeyMakarenko/fbthrift,fengshao0907/fbthrift,HankFaan/fbthrift,Orvid/fbthrift,Orvid/fbthrift,chjp2046/fbthrift,getyourguide/fbthrift,getyourguide/fbthrift,jesboat/fbthrift,soumith/fbthrift,LinusU/fbthrift,LinusU/fbthrift,Orvid/fbthrift,Orvid/fbthrift,chjp2046/fbthrift,getyourguide/fbthrift,SergeyMakarenko/fbthrift,LinusU/fbthrift,soumith/fbthrift,uber/fbthrift,fengshao0907/fbthrift,HankFaan/fbthrift,project-zerus/fbthrift,jesboat/fbthrift,HankFaan/fbthrift,soumith/fbthrift,uber/fbthrift,jesboat/fbthrift,maxwell-demon/fbthrift,kangkot/fbthrift,getyourguide/fbthrift,getyourguide/fbthrift,kangkot/fbthrift,sinjar666/fbthrift,SergeyMakarenko/fbthrift,uber/fbthrift,Orvid/fbthrift,soumith/fbthrift,jesboat/fbthrift,chjp2046/fbthrift,raphaelamorim/fbthrift,raphaelamorim/fbthrift,uber/fbthrift,guker/fbthrift,facebook/fbthrift,project-zerus/fbthrift,LinusU/fbthrift,soumith/fbthrift,Orvid/fbthrift,chjp2046/fbthrift,HankFaan/fbthrift,guker/fbthrift,SergeyMakarenko/fbthrift,jesboat/fbthrift,fengshao0907/fbthrift,jesboat/fbthrift,guker/fbthrift,raphaelamorim/fbthrift,sinjar666/fbthrift,sinjar666/fbthrift,SergeyMakarenko/fbthrift,uber/fbthrift,getyourguide/fbthrift,facebook/fbthrift,guker/fbthrift,project-zerus/fbthrift,fengshao0907/fbthrift,Orvid/fbthrift,chjp2046/fbthrift,chjp2046/fbthrift,maxwell-demon/fbthrift,kangkot/fbthrift,maxwell-demon/fbthrift,raphaelamorim/fbthrift,Orvid/fbthrift,sinjar666/fbthrift,kangkot/fbthrift,jesboat/fbthrift,Orvid/fbthrift,jesboat/fbthrift,uber/fbthrift,raphaelamorim/fbthrift,raphaelamorim/fbthrift,maxwell-demon/fbthrift,chjp2046/fbthrift,uber/fbthrift,SergeyMakarenko/fbthrift,LinusU/fbthrift,soumith/fbthrift,HankFaan/fbthrift,maxwell-demon/fbthrift,HankFaan/fbthrift,facebook/fbthrift,HankFaan/fbthrift,getyourguide/fbthrift,LinusU/fbthrift,project-zerus/fbthrift,SergeyMakarenko/fbthrift,fengshao0907/fbthrift,sinjar666/fbthrift,project-zerus/fbthrift,raphaelamorim/fbthrift,getyourguide/fbthrift,sinjar666/fbthrift,fengshao0907/fbthrift,maxwell-demon/fbthrift,facebook/fbthrift,guker/fbthrift,guker/fbthrift,chjp2046/fbthrift,HankFaan/fbthrift,maxwell-demon/fbthrift,project-zerus/fbthrift,guker/fbthrift,HankFaan/fbthrift,kangkot/fbthrift,uber/fbthrift,maxwell-demon/fbthrift,guker/fbthrift,soumith/fbthrift,project-zerus/fbthrift,guker/fbthrift,soumith/fbthrift,facebook/fbthrift,chjp2046/fbthrift,jesboat/fbthrift,HankFaan/fbthrift,sinjar666/fbthrift,fengshao0907/fbthrift,jesboat/fbthrift,project-zerus/fbthrift,facebook/fbthrift,project-zerus/fbthrift,maxwell-demon/fbthrift,jesboat/fbthrift,raphaelamorim/fbthrift,sinjar666/fbthrift,SergeyMakarenko/fbthrift,chjp2046/fbthrift,Orvid/fbthrift,kangkot/fbthrift,fengshao0907/fbthrift,maxwell-demon/fbthrift,raphaelamorim/fbthrift,fengshao0907/fbthrift,LinusU/fbthrift,getyourguide/fbthrift,kangkot/fbthrift,LinusU/fbthrift,SergeyMakarenko/fbthrift,getyourguide/fbthrift,getyourguide/fbthrift,LinusU/fbthrift,chjp2046/fbthrift,raphaelamorim/fbthrift,jesboat/fbthrift,LinusU/fbthrift,kangkot/fbthrift,maxwell-demon/fbthrift,kangkot/fbthrift,LinusU/fbthrift,fengshao0907/fbthrift,guker/fbthrift,HankFaan/fbthrift,raphaelamorim/fbthrift,SergeyMakarenko/fbthrift,soumith/fbthrift,kangkot/fbthrift,sinjar666/fbthrift,sinjar666/fbthrift,project-zerus/fbthrift,facebook/fbthrift,uber/fbthrift,uber/fbthrift,getyourguide/fbthrift,facebook/fbthrift,kangkot/fbthrift,fengshao0907/fbthrift,Orvid/fbthrift,soumith/fbthrift,project-zerus/fbthrift,chjp2046/fbthrift,sinjar666/fbthrift,SergeyMakarenko/fbthrift,uber/fbthrift,project-zerus/fbthrift,facebook/fbthrift