fix(dropdown): add safety check for setIsOpen
fix(dropdown): add safety check for setIsOpen

- Ensure `setIsOpen` is a function, due to it optionally being falsy

Closes #4030

xiwc/bootstrap-1,christor/bootstrap,woshiyigebing/bootstrap,GirishKumrawat/bootstrap,Marwzoor/bootstrap,benhalverson/bootstrap,kirning/bootstrap-1,pkdevbox/angular-ui-bootstrap,ChinnasamyM/bootstrap,SystemDisc/bootstrap,imskojs/bootstrap,tmcgee123/bootstrap,benhalverson/bootstrap,fmccown/bootstrap,davincho/bootstrap,qpitlove/bootstrap,azahreba/bootstrap,tmcgee123/bootstrap,fmccown/bootstrap,spadgett/bootstrap,karelcallens/bootstrap,teng2015/bootstrap,shadowdaw/bootstrap,cgat/bootstrap,Lohann/bootstrap,2363140194/bootstrap,universsky/bootstrap-1,kemapak/bootstrap,deeg/bootstrap,Foxandxss/bootstrap,justin-john/bootstrap-1,guaerguagua/bootstrap,WXwangxin/bootstrap,davious/angular-ui-bootstrap,connyay/bootstrap,mykhaylo-/bootstrap,mufl1h/bootstrap,cdrewery/bootstrap,freejavaster/bootstrap,Zazulei/bootstrap,infowrap/bootstrap,MetSystem/bootstrap,ksheedlo/bootstrap,succ1984/bootstrap,gfaceless/bootstrap,yonglehou/bootstrap-1,eftakharali/bootstrap,bsiddiqui/bootstrap,SatvikPurohit/bootstrap,maoli1110/bootstrap,nathan-j-brenner/bootstrap-1,karelcallens/bootstrap,TORO-IO/bootstrap-1,carlosjunior/bootstrap,connyay/bootstrap,realityking/ui-bootstrap,burlhock/bootstrap,qpitlove/bootstrap,MetSystem/bootstrap,suryasingh/bootstrap,fernando-sendMail/bootstrap,daviesgeek/bootstrap,yukisan/bootstrap,reiniergs/bootstrap,Gailby/bootstrap,wuhoujun/bootstrap,rasulnz/bootstrap,hyoda/bootstrap,jackRogers/bootstrap,zhaokunfay/bootstrap,Kpler/bootstrap,thomassorensen/bootstrap,obivandamme/bootstrap,Lincoln-xzc/angular-ui-bootstrap,Lincoln-xzc/angular-ui-bootstrap,yonglehou/bootstrap-1,woshiyigebing/bootstrap,Bugagazavr/bootstrap,atulc007/bootstrap-1,DenisCloutier/bootstrap,SimilarWeb/bootstrap,Nekle/bootstrap,rasulnz/bootstrap,kongx73/bootstrap,zhaokunfay/bootstrap,vfiles/bootstrap,cgvarela/bootstrap-1,alokpradhan/bootstrap,JonFerrera/ui-bootstrap,shiftagent/ui-bootstrap,MikhailNazarov/bootstrap,rajesh-frontendengineer/bootstrap-1,tobigun/bootstrap,rodrigues-daniel/bootstrap,pdsoftplan/bootstrap,yjukaku/bootstrap,hyoda/bootstrap,WXwangxin/bootstrap,SatvikPurohit/bootstrap,rgolea/bootstrap,pkdevbox/angular-ui-bootstrap,leyanlo/bootstrap,SimilarWeb/bootstrap,elijah513/bootstrap,dabos-GFI/angular-ui-bootstrap,Schibum/bootstrap,xiwc/bootstrap-1,SystemDisc/bootstrap,iamcbh/bootstrap,oliversalzburg/bootstrap,Lexxville/bootstrap-1,xzoth/bootstrap,mabi/bootstrap,fjg1989/bootstrap,Foxandxss/bootstrap,nathan-j-brenner/bootstrap-1,krossoverintelligence/bootstrap,jaydiablo/bootstrap,atulc007/bootstrap-1,eftakharali/bootstrap,fpipita/bootstrap,wuwei111467/bootstrap,edivancamargo/bootstrap,mohuk/bootstrap,MikhailNazarov/bootstrap,nobitagit/bootstrap,jczerwinski/bootstrap-1,guaido79/bootstrap,xzoth/bootstrap,icfantv/bootstrap,Kpler/bootstrap,DiHuang1986/bootstrap,292388900/bootstrap,Xephi/bootstrap,rajesh-frontendengineer/bootstrap-1,dmc2015/bootstrap,vsternbach/bootstrap,realityking/ui-bootstrap,pkdevbox/bootstrap-1,noellejung/bootstrap,yjukaku/bootstrap,liiza/bootstrap,elancom/bootstrap-1,mohuk/bootstrap,mabi/bootstrap,ahsanbagwan/bootstrap,folsom-labs/bootstrap,carlosjunior/bootstrap,mykhaylo-/bootstrap,finkcloud/bootstrap,freejavaster/bootstrap,eduncan26/bootstrap,Anirudhk94/bootstrap,gbasto/bootstrap,leyanlo/bootstrap,angular-ui/bootstrap,pireerliu/bootstrap,drocbuster/My_AngularJS_Repo,angular-ui/bootstrap,davereed/bootstrap,rodrigues-daniel/bootstrap,gbasto/bootstrap,christor/bootstrap,rhamid/bootstrap-1,KingMario/bootstrap-1,yubin-huang/bootstrap,nlwillia/bootstrap,mikesavior/bootstrap,deeg/bootstrap,Lexxville/bootstrap-1,pkdevbox/bootstrap-1,guaido79/bootstrap,lancerushing/bootstrap,liqingzhu/bootstrap,voyagecontrol/bootstrap,BookingBug/bootstrap,vfiles/bootstrap,maoli1110/bootstrap,inukshuk/bootstrap,pmalikbtech/bootstrap,Bugagazavr/bootstrap,inoxis91/bootstrap,DenisCloutier/bootstrap,elijah513/bootstrap,Vreasy/bootstrap,edivancamargo/bootstrap,linuxvom/bootstrap,madhudskumar/bootstrap,fabg21/bootstrap,universsky/bootstrap-1,Nekle/bootstrap,linuxvom/bootstrap,SandeepSikhakolli/bootstrap,parikmaher534/bootstrap,wesleycho/bootstrap,obivandamme/bootstrap,gorork/bootstrap,succ1984/bootstrap,sullivanpt/bootstrap,krossoverintelligence/bootstrap,josheche/bootstrap-1,reiniergs/bootstrap,vsternbach/bootstrap,Servoy/bootstrap,eduncan26/bootstrap,fabg21/bootstrap,filso/bootstrap,zepheiryan/bootstrap,Farael49/bootstrap,dmc2015/bootstrap,Den-dp/bootstrap,ehteshamkafeel/bootstrap,folsom-labs/bootstrap,liqingzhu/bootstrap,franzherzog/bootstrap,caoruiy/bootstrap,Jchavez/bootstrap-1,codedogfish/angular-ui-bootstrap,tobigun/bootstrap,shootermv/bootstrap,DiHuang1986/bootstrap,kemapak/bootstrap,BookingBug/bootstrap,parikmaher534/bootstrap,davious/angular-ui-bootstrap,Vreasy/bootstrap,cgat/bootstrap,shihang0001/bootstrap,matteopic/bootstrap,nicklv/bootstrap,sullivanpt/bootstrap,gorork/bootstrap,ahsanbagwan/bootstrap,miiihi/bootstrap,davincho/bootstrap,JDeuker/bootstrap,themifycloud/bootstrap,gato-gordo/bootstrap,stereocilia/bootstrap,inukshuk/bootstrap,birdy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