Request#error() now accepts a callback function
Request#error() now accepts a callback function

A common idiom is / will be to accept a callback function in most cases
so this will help to keep things DRY

pshomov/express,nodejs-camp/booklog-jason,nodejs-camp/booklog-linkchen,PeterWangPo/express,llwanghong/express,heicx/express,dsupera13/express,BaggersIO/express,BaggersIO/express,isaacs/express,HXYNODE/express,friederbluemle/express,andrejewski/express,sarvex/express,abdulhannanali/express,mauricionr/express,nodejs-camp/booklog-archer,qitianchan/express,btleffler/express,abhi3/express,abdulhannanali/express,adjohnson916/express,ifraixedes/express,samuelcastro/express,fuse-mars/express,Riokai/express,nodejs-camp/booklog-Zak,gnowoel/express,gnowoel/express,Jonekee/express,tjmehta/express,angelsanz/express,ericlu88/express,lmtdit/express,XueQian/express,robomc/express,stoskov/express,kunalpict/express,simplyianm/express,coreypnorris/express,kentcdodds/express,philxia/ex-tst-framework,wtony/express,soyuka/express,juandav/express,andrejewski/express,stevemao/express,hanweifish/express,vidyar/express,bercanozcan/express,lemelon/express,dongseop/express,jinghuizhai/express,kylezhang/express,pstrike/express,RanadeepPolavarapu/express,auth0/express,nathan818fr/express,pathirana/express,neomadara/express,xtidt/express,maraoz/express,r14r/fork_express_master,Kevnz/express,stewartml/express,nodejs-camp/booklog-leo,vinodhalaharvi/express,philxia/ex-tst-framework,buildsample/express,blakeembrey/express,LestaD/express,topaxi/express,lian774739140/express,nodejs-camp/booklog-mora,kubrickology/express,hpcslag/express,nbeydoon/express,gretac/express,za-creature/express,awronka/express,fanzetao/express,junxiong/express,smcmurray/express,nodejs-camp/booklog-archer,christopheranderson/express,fakedarren/express,jenia0jenia/express,jenalgit/express,fuse-mars/express,nodejs-camp/booklog-tonebeta,hacksparrow/express,heicx/express,Eric-Vandenberg/express,listepo/express,hanqingnan/express,chrisinajar/express,microlv/express,leiqiang75/express,ralic/express,kawanet/express,MoraLin/mora-test,grigorkh/express,abhi3/express,fineday32/express,ci-test2/express,nodejs-camp/booklog-leo,nodejs-camp/booklog-homa,fineday32/express,qq645381995/express,frank06/express,blakeembrey/express,swarajgiri/express,hpcslag/express,jymsy/express,vnglst/express,JulyZhu/express,hl198181/express,nodejs-camp/booklog-chenyou,friederbluemle/express,shanawarkhan/express,hdngr/express,evilboss/express,r14r/fork_express_master,RanadeepPolavarapu/express,fakedarren/express,rgrove/express,isaacs/express,dotnetCarpenter/express,Riokai/express,microlv/express,listepo/express,Talkyunyun/express,buildsample/express,neomadara/express,emvici/emvici-reqres-tify,r14r-work/fork_express_master,lemelon/express,devgeniem/express,micha149/express,sujianping/express,pshomov/express,xiaofuzi/express,youprofit/express,udhayam/express,LestaD/express,Faiz7412/express,drzorm/express,nodejs-camp/booklog-ben,nodejs-camp/booklog-chle,fanzetao/express,brianloveswords/express,nodejs-camp/booklog-Zak,CrazySherman/express,blairzhang/express,TestingCI/express,philxia/ex-tst-framework,baldurh/express,dafabulousteach/express,dotnetCarpenter/express,pathirana/express,listepo/express,supasate/express,corporateanon/express,svnh/express,lian774739140/express,RickyDan/express,adjohnson916/express,angelsanz/express,grigorkh/express,TestingCI/express,junxiong/express,grigorkh/express,juanpastas/express,dreamingblackcat/express,bjrmatos/express,devgeniem/express,auth0/express,featurist/express,qitianchan/express,nodejs-camp/booklog-ansaga,jinghuizhai/express,abhi3/express,nodejs-camp/booklog-ben,nodejs-camp/booklog-ansaga,vidyar/express,caiocutrim/express,rupanjanbaidya/express,dongooo/express,KodkodGates/express,JulyZhu/express,danielrohers/express,stoskov/express,Lexine/express,Ivanwangcy/express,blairzhang/express,Ivanwangcy/express,sarvex/express,dieuly/express,tfe/express,RickyDan/express,featurist/express,nodejs-camp/booklog-polo,blairzhang/express,nodejs-camp/booklog-jollen,PeterWangPo/express,thepont/express,MoraLin/mora-test,shanawarkhan/express,WangCao/express,Flip120/express,jenia0jenia/express,demohi/express,lmtdit/express,gnowoel/express,za-creature/express,WebStyle/express,1amageek/express,fakedarren/express,countdracular/express,youprofit/express,KodkodGates/express,swarajgiri/express,wtony/express,1amageek/express,igarciaes/express,ZackBotkin/express,blakeembrey/express,simudream/express,juandav/express,FernAbby/express,srichatala/express,BaggersIO/express,nodejs-camp/booklog-jason,WebStyle/express,jimmykuo/express,nodejs-camp/booklog-tonebeta-update,hightechweb/express,chuym/express,flomotlik/express,rupanjanbaidya/express,samuelcastro/express,1amageek/express,tianhengzhou/express,dsupera13/express,tianhengzhou/express,dafabulousteach/express,rgrove/express,Ju2ender/express,mimaidms/express,corporateanon/express,Jonekee/express,v10258/express,dreamingblackcat/express,cflynn07/express,micha149/express,michaeljunlove/express,LestaD/express,swstack/express,coreypnorris/express,saisai/express,xtidt/express,WangCao/express,YR/express,Faiz7412/express,ahdinosaur/express,XueQian/express,tyler-johnson/express,Ju2ender/express,soyuka/express,cflynn07/express,r14r-work/fork_express_master,jinghuizhai/express,FernAbby/express,Talkyunyun/express,christopheranderson/express,hightechweb/express,ralic/express,wesleytodd/express,pstrike/express,maraoz/express,dotnetCarpenter/express,evanlucas/express,hacksparrow/express,sarvex/express,wtony/express,kentcdodds/express,hdngr/express,1verson/express,za-creature/express,dgofman/express,strongloop/express,aifeld/express,hanweifish/express,wesleytodd/express,nodejs-camp/booklog-chle,kylezhang/express,smcmurray/express,luxe-eng/valet-express.express,leiqiang75/express,nodejs-camp/booklog-polo,topaxi/express,gdeividas/express,tyler-johnson/express,abdulhannanali/express,hpcslag/express,jymsy/express,stewartml/express,llwanghong/express,kunalpict/express,Ju2ender/express,nodejs-camp/booklog-ausir,robomc/express,nodejs-camp/booklog-chenyou,evilboss/express,nodejs-camp/booklog-ausir,nodejs-camp/booklog-linkchen,caiocutrim/express,bjrmatos/express,methuz/express,frank06/express,nodejs-camp/booklog-tonebeta-update,codeforgeek/express,mcanthony/express,blainsmith/express,junxiong/express,VegeChou/express,topaxi/express,Kevnz/express,vnglst/express,Matrixbirds/express,ericlu88/express,ahdinosaur/express,Faiz7412/express,lmtdit/express,baldurh/express,vinodhalaharvi/express,yinhe007/express,kawanet/express,dafabulousteach/express,awronka/express,ifraixedes/express,supasate/express,PUSEN/express,svnh/express,simudream/express,1verson/express,dgofman/express,ci-test2/express,HXYNODE/express,nodejs-camp/booklog-s890506,expressjs/express,featurist/express,sibura/express,frootloops/express,mikewesthad/express,nodejs-camp/booklog-mora,weilixia/express,chuym/express,Matrixbirds/express,WangCao/express,juanpastas/express,nodejs-camp/booklog-s890506,nodejs-camp/booklog-tonebeta,nbeydoon/express,blainsmith/express,stevemao/express,angelsanz/express,Eric-Vandenberg/express,ZackBotkin/express,thepont/express,devgeniem/express,jenalgit/express,danielrohers/express,andriyl/express,Flip120/express,udhayam/express,benshiue/booklog-ben,sujianping/express,sibura/express,Lexine/express,methuz/express,elkingtonmcb/express,v10258/express,simudream/express,Eric-Vandenberg/express,kylezhang/express,nodejs-camp/booklog-polo,friederbluemle/express,corporateanon/express,swarajgiri/express,v10258/express,buildsample/express,nbeydoon/express,yinhe007/express,nathan818fr/express,luxe-eng/valet-express.express,jenia0jenia/express,nodejs-camp/booklog-jollen,supasate/express,countdracular/express,simplyianm/express,dieuly/express,YR/express,smcmurray/express,coreypnorris/express,gretac/express,maraoz/express,codeforgeek/express,XueQian/express,bercanozcan/express,flomotlik/express,gdeividas/express,benshiue/booklog-ben,stevemao/express,Flip120/express,VegeChou/express,stewartml/express,srichatala/express,dongseop/express,drzorm/express,luxe-eng/valet-express.express,xiaofuzi/express,kubrickology/express,elkingtonmcb/express,dreamingblackcat/express,CrazySherman/express,mcanthony/express,btleffler/express,saisai/express,PUSEN/express,hanqingnan/express,chrisinajar/express,qitianchan/express,hdngr/express,chrisinajar/express,dongooo/express,mikewesthad/express,Haru1990/express,aifeld/express,Haru1990/express,philxia/ex-tst-framework,tjmehta/express,frootloops/express,youprofit/express,ZackBotkin/express,svnh/express,mauricionr/express,andriyl/express,michaeljunlove/express,stoskov/express,expressjs/express,TestingCI/express,dongseop/express,qq645381995/express,evanlucas/express,evilboss/express,weilixia/express,jenalgit/express,nodejs-camp/booklog-homa,bercanozcan/express,demohi/express,strongloop/express,vnglst/express,igarciaes/express,Riokai/express,vidyar/express,KodkodGates/express,qq645381995/express,xiaofuzi/express,mimaidms/express,michaeljunlove/express,swstack/express,kunalpict/express,vinodhalaharvi/express,hl198181/express,jimmykuo/express,ci-test2/express