Add a non-decorator version of the error handler register function
Add a non-decorator version of the error handler register function

The main application object has a register_error_handler function
which mirrors the decorator's functionality. According to the principle
of least surprise, make sure blueprints also have this convenience function.

onetinyr/flask,onetinyr/flask,jenalgit/flask,lynget/flask,felipefuka/flask,alexwidener/flask,RohithKP/flask,Faiz7412/flask,XGiton/flask,kuhli/flask,pallets/flask,dominjune/flask,qinfengsuiyu/flask,jonieli/flask,pallets/flask,xiaoshaozi52/flask,drewja/flask,ryandvill/flask,mrdon/flask,alanhamlett/flask,liuyi1112/flask,artleaf/flask,TylerB24890/flask,bodefuwa/flask,gangeshwark/flask,alexwidener/flask,wtorcasoGB/flask,nZac/flask,iamantee/flask,garaden/flask,huwenhui/flask,VShangxiao/flask,ZacariasBendeck/flask,antsar/flask,wangjun/flask,margguo/flask,liaoqingwei/flask,nwags/flask,homeworkprod/flask,vivekanand1101/flask,zailushangde/flask,Ricardo666666/flask,zoyanhui/flask,ankravch/flask,Faiz7412/flask,jorpramo/flask,Papa2k15/flask,raven47git/flask,liaoqingwei/flask,rollingstone/flask,dawran6/flask,JingZhou0404/flask,treedledee/flask,gbolahanalade/flask,pxzhenren/flask,lyn233/flask,vivekanand1101/flask,mrdon/flask,nwags/flask,cgvarela/flask,zoyanhui/flask,liaoqingwei/flask,gilesburnfield/flask,aniketshukla/flask,Ricardo666666/flask,wldtyp/flask,oculardexterity/flask,wilbert-abreu/flask,tangfeng1/flask,tony/flask,cgvarela/flask,mysweet/flask,godfreyy/flask,GavinCruise/flask,moluzhang/flask,JamesTFarrington/flask,liukaijv/flask,xiaoshaozi52/flask,pinkpet/flask,suppandi/flask,xujianhai/flask,ryandvill/flask,visaxin/flask,luvten/flask,karlw00t/flask,TylerB24890/flask,mitchfriedman/flask,postelin/flask,gilesburnfield/flask,Faiz7412/flask,jenalgit/flask,abdulbaqi/flask,grayswand1r/flask,skmezanul/flask,grayswand1r/flask,Eagles2F/flask,jonatanblue/flask,tjxiter/flask,karen-wang/flask,postelin/flask,s7v7nislands/flask,chenrenyi/flask,SsangYoon/Flask,mujiatong/flask,visaxin/flask,anujk3/flask,wtl-zju/flask,HeyItsAlan/flask,SsangYoon/Flask,drewja/flask,niima/flask,ZacariasBendeck/flask,s7v7nislands/flask,xujianhai/flask,nju520/flask,liuyi1112/flask,bodefuwa/flask,VShangxiao/flask,jawed123/flask,skmezanul/flask,cheesecake4392/flask,onetinyr/flask,nZac/flask,elelianghh/flask,hoatle/flask,lord63-forks/flask,ezequielo/flask,EasonYi/flask,sixpi/flask,Parkayun/flask,cheesecake4392/flask,fengsp/flask,wudafucode/flask,kuku940/flask,chuijiaolianying/flask,chuijiaolianying/flask,dawran6/flask,q1ang/flask,flabe81/flask,WSDC-NITWarangal/flask,jstacoder/flask,LonglyCode/flask,TylerB24890/flask,jeezybrick/flask,kyle-sorensen/flask,beni55/flask,raven47git/flask,horica-ionescu/flask,vishnugonela/flask,chenrenyi/flask,sonnyhu/flask,ffsdmad/flask,ezequielo/flask,hyunchel/flask,rollingstone/flask,fevxie/flask,pallets/flask,edcomstock/flask,happyspace/flask,Endika/flask,WSDC-NITWarangal/flask,Parkayun/flask,margguo/flask,chuijiaolianying/flask,dhruvsrivastava/flask,rawrgulmuffins/flask,theo-l/flask,sam-tsai/flask,anujk3/flask,q1ang/flask,szymonm/flask,lynget/flask,fkazimierczak/flask,GavinCruise/flask,visaxin/flask,anujk3/flask,luvten/flask,aniketshukla/flask,liuyi1112/flask,jawed123/flask,brianbeale/flask,ABaldwinHunter/flask-clone-classic,ezequielo/flask,alanhamlett/flask,fanshaohua-fan/flask,lyn233/flask,gangeshwark/flask,Eagles2F/flask,jorpramo/flask,fevxie/flask,postelin/flask,ankurpandey/flask,garaden/flask,rawrgulmuffins/flask,Endika/flask,kyle-sorensen/flask,wudafucode/flask,tripathi62674/flask,pledo/flask,EasonYi/flask,Freebird2014/flask,chenke91/flask,cliu-aa/flask,mitsuhiko/flask,felipefuka/flask,wtl-zju/flask,godfreyy/flask,jonatanblue/flask,AndreaEdwards/flask,jiimaho/flask,fanshaohua-fan/flask,lalinsky/flask,artleaf/flask,algoStruct/flask,fengsp/flask,antsar/flask,tangfeng1/flask,jorpramo/flask,algoStruct/flask,stephaniemertz/flask,flamelizard/flask,tcnoviembre2013/flask,karlw00t/flask,happyspace/flask,fkazimierczak/flask,warm200/flask,suppandi/flask,horica-ionescu/flask,pxzhenren/flask,godfreyy/flask,mujiatong/flask,wangjun/flask,ghhong1986/flask,jstacoder/flask,XGiton/flask,szymonm/flask,vishnugonela/flask,RohithKP/flask,vishnugonela/flask,fkazimierczak/flask,homeworkprod/flask,hoatle/flask,liukaijv/flask,justanr/flask,auready/flask,VShangxiao/flask,sixpi/flask,chenke91/flask,s7v7nislands/flask,jonieli/flask,mitchfriedman/flask,mAzurkovic/flask,stephaniemertz/flask,dhruvsrivastava/flask,gangeshwark/flask,tangfeng1/flask,justanr/flask,chenke91/flask,suppandi/flask,huwenhui/flask,ankurpandey/flask,robertglen/flask,tripathi62674/flask,mrdon/flask,jeezybrick/flask,ryandvill/flask,artleaf/flask,blankme/flask,Ricardo666666/flask,GavinCruise/flask,SsangYoon/Flask,bluedazzle/flask,oculardexterity/flask,zailushangde/flask,ffsdmad/flask,flabe81/flask,justanr/flask,oculardexterity/flask,tristanfisher/flask,jiimaho/flask,qinfengsuiyu/flask,sonnyhu/flask,abdulbaqi/flask,gaomingnudt/gm-flask2.0,ghhong1986/flask,wtorcasoGB/flask,ABaldwinHunter/flask-clone-classic,arvinls/flask,elelianghh/flask,tristanfisher/flask,edcomstock/flask,theo-l/flask,blankme/flask,ankravch/flask,luzzyzhang/flask,moluzhang/flask,AndreaEdwards/flask,kuhli/flask,treedledee/flask,mysweet/flask,AvivC/flask,EasonYi/flask,nju520/flask,karen-wang/flask,iamantee/flask,JamesTFarrington/flask,mAzurkovic/flask,AndreaEdwards/flask,happyspace/flask,jstacoder/flask,adrianmoisey/cptdevops,flamelizard/flask,gbolahanalade/flask,lalinsky/flask,arvinls/flask,szymonm/flask,HeyItsAlan/flask,adrianmoisey/cptdevops,niima/flask,robertglen/flask,luzzyzhang/flask,kyle-sorensen/flask,tony/flask,kuku940/flask,tcnoviembre2013/flask,sam-tsai/flask,cliu-aa/flask,AvivC/flask,jonieli/flask,dominjune/flask,ankurpandey/flask,wldtyp/flask,warm200/flask,Freebird2014/flask,pledo/flask,karen-wang/flask,beni55/flask,jenalgit/flask,drewja/flask,mrdon/flask,gaomingnudt/gm-flask2.0,DesQi/flask,warm200/flask,sage417/flask,alanhamlett/flask,DesQi/flask,raven47git/flask,pinkpet/flask,tjxiter/flask,algoStruct/flask,hyunchel/flask,sage417/flask,JingZhou0404/flask,LonglyCode/flask,auready/flask,brianbeale/flask,bluedazzle/flask,mitsuhiko/flask,Papa2k15/flask,lord63-forks/flask,nju520/flask,wilbert-abreu/flask