[hack] Avoid usage of `assert false` in Typing_alias
[hack] Avoid usage of `assert false` in Typing_alias

Reviewed By: @dlreeves

Differential Revision: D2327287

Drooids/flow,gabelevi/flow,Drooids/flow,claudiopro/flow,darioajr/flow,jeffmo/flow,facebook/flow,lyip1992/flow,Eyyub/flow,shiftcars/flow,cesarandreu/flow,fletcherw/flow,d14b3l/flow,gabro/flow,MichaelDeBoey/flow,asivitz/flow,gabelevi/flow,nmote/flow,nmote/flow,CJstar/flow,ylu1317/flow,ylu1317/flow,lyip1992/flow,popham/flow,AprilArcus/flow,gabelevi/flow,chenglou/flow,dv/flow,fletcherw/flow,jgrund/flow,ForbesLindesay/flow,MichaelDeBoey/flow,popham/flow,JonathanUsername/flow,JonathanUsername/flow,CJstar/flow,gabro/flow,dv/flow,samwgoldman/flow,TiddoLangerak/flow,rafaelstz/flow,samwgoldman/flow,asivitz/flow,danvk/flow,samwgoldman/flow,ianobermiller/flow,Wanderfalke/flow,paulshen/flow,mcanthony/flow-type,mroch/flow,jgrund/flow,MichaelDeBoey/flow,d14b3l/flow,Fresheyeball/flow,cesarandreu/flow,gabro/flow,fletcherw/flow,CJstar/flow,gabro/flow,Drooids/flow,Fresheyeball/flow,AprilArcus/flow,chenglou/flow,mroch/flow,samwgoldman/flow,asivitz/flow,chenglou/flow,Eyyub/flow,JohnyDays/flow,TiddoLangerak/flow,rafaelstz/flow,cesarandreu/flow,jdelStrother/flow,popham/flow,d14b3l/flow,claudiopro/flow,jgrund/flow,popham/flow,ForbesLindesay/flow,danvk/flow,Fresheyeball/flow,chenglou/flow,gabelevi/flow,paulshen/flow,graue/flow,MichaelDeBoey/flow,jeffmo/flow,OCamlPro/flow,siddhartharay007/flow,ianobermiller/flow,OCamlPro/flow,Wanderfalke/flow,rafaelstz/flow,gabelevi/flow,darioajr/flow,facebook/flow,jamesgpearce/flow,ianobermiller/flow,jgrund/flow,d14b3l/flow,shiftcars/flow,TiddoLangerak/flow,asivitz/flow,jamesgpearce/flow,facebook/flow,OCamlPro/flow,samwgoldman/flow,mroch/flow,gabro/flow,fletcherw/flow,danvk/flow,gabelevi/flow,jdelStrother/flow,gabelevi/flow,KevinTCoughlin/flow,graue/flow,mcanthony/flow-type,jeffutter/flow,JohnyDays/flow,shiftcars/flow,mcanthony/flow-type,TiddoLangerak/flow,AgentME/flow,claudiopro/flow,ForbesLindesay/flow,AgentME/flow,jeffmo/flow,mcanthony/flow-type,dv/flow,jeffmo/flow,CJstar/flow,ForbesLindesay/flow,nmote/flow,graue/flow,lyip1992/flow,AprilArcus/flow,jamesgpearce/flow,ForbesLindesay/flow,OCamlPro/flow,shiftcars/flow,darioajr/flow,JonathanUsername/flow,jgrund/flow,JonathanUsername/flow,fletcherw/flow,paulshen/flow,mroch/flow,jeffutter/flow,JohnyDays/flow,chenglou/flow,jdelStrother/flow,jamesgpearce/flow,jamesgpearce/flow,jgrund/flow,darioajr/flow,facebook/flow,popham/flow,jdelStrother/flow,Eyyub/flow,nmote/flow,TiddoLangerak/flow,popham/flow,dv/flow,ianobermiller/flow,samwgoldman/flow,gabro/flow,KevinTCoughlin/flow,jamesgpearce/flow,jeffutter/flow,nmote/flow,Eyyub/flow,jeffmo/flow,KevinTCoughlin/flow,rafaelstz/flow,MichaelDeBoey/flow,siddhartharay007/flow,ylu1317/flow,siddhartharay007/flow,Fresheyeball/flow,Wanderfalke/flow,Drooids/flow,samwgoldman/flow,rafaelstz/flow,claudiopro/flow,facebook/flow,AprilArcus/flow,mroch/flow,siddhartharay007/flow,chenglou/flow,facebook/flow,mroch/flow,graue/flow,jeffmo/flow,graue/flow,AprilArcus/flow,AprilArcus/flow,mroch/flow,AgentME/flow,danvk/flow,Wanderfalke/flow,JohnyDays/flow,shiftcars/flow,cesarandreu/flow,JonathanUsername/flow,jamesgpearce/flow,JonathanUsername/flow,nmote/flow,lyip1992/flow,KevinTCoughlin/flow,AgentME/flow,JonathanUsername/flow,ForbesLindesay/flow,facebook/flow,graue/flow,popham/flow,d14b3l/flow,nmote/flow,AgentME/flow,claudiopro/flow,d14b3l/flow,jeffutter/flow,ylu1317/flow,paulshen/flow,jdelStrother/flow,ylu1317/flow,fletcherw/flow,shiftcars/flow,jdelStrother/flow