base.html: Add check for undefined user_profile.
base.html: Add check for undefined user_profile.

The previous code that neglected this check worked with the Django
templating engine but will not work with Jinja2.

dawran6/zulip,j831/zulip,JPJPJPOPOP/zulip,timabbott/zulip,isht3/zulip,PhilSk/zulip,TigorC/zulip,synicalsyntax/zulip,rishig/zulip,rishig/zulip,umkay/zulip,Galexrt/zulip,blaze225/zulip,AZtheAsian/zulip,niftynei/zulip,SmartPeople/zulip,vikas-parashar/zulip,vabs22/zulip,dhcrzf/zulip,peiwei/zulip,zacps/zulip,samatdav/zulip,paxapy/zulip,brainwane/zulip,susansls/zulip,mahim97/zulip,sup95/zulip,dhcrzf/zulip,souravbadami/zulip,aakash-cr7/zulip,peguin40/zulip,joyhchen/zulip,jrowan/zulip,cosmicAsymmetry/zulip,dattatreya303/zulip,brockwhittaker/zulip,niftynei/zulip,kou/zulip,tommyip/zulip,sharmaeklavya2/zulip,peiwei/zulip,rht/zulip,punchagan/zulip,PhilSk/zulip,paxapy/zulip,brainwane/zulip,rht/zulip,joyhchen/zulip,Galexrt/zulip,hackerkid/zulip,christi3k/zulip,Galexrt/zulip,Galexrt/zulip,vabs22/zulip,souravbadami/zulip,synicalsyntax/zulip,zacps/zulip,jainayush975/zulip,brainwane/zulip,j831/zulip,Diptanshu8/zulip,aakash-cr7/zulip,Juanvulcano/zulip,Juanvulcano/zulip,dawran6/zulip,SmartPeople/zulip,isht3/zulip,Vallher/zulip,samatdav/zulip,vaidap/zulip,rishig/zulip,Diptanshu8/zulip,dattatreya303/zulip,AZtheAsian/zulip,mahim97/zulip,blaze225/zulip,aakash-cr7/zulip,Diptanshu8/zulip,rishig/zulip,andersk/zulip,KingxBanana/zulip,dattatreya303/zulip,susansls/zulip,isht3/zulip,ryanbackman/zulip,susansls/zulip,synicalsyntax/zulip,sup95/zulip,jainayush975/zulip,peguin40/zulip,tommyip/zulip,Jianchun1/zulip,dhcrzf/zulip,peguin40/zulip,jrowan/zulip,jainayush975/zulip,Juanvulcano/zulip,eeshangarg/zulip,mohsenSy/zulip,Juanvulcano/zulip,timabbott/zulip,Jianchun1/zulip,peiwei/zulip,jainayush975/zulip,j831/zulip,brainwane/zulip,andersk/zulip,showell/zulip,punchagan/zulip,peiwei/zulip,SmartPeople/zulip,verma-varsha/zulip,jackrzhang/zulip,ahmadassaf/zulip,kou/zulip,Vallher/zulip,rht/zulip,timabbott/zulip,amanharitsh123/zulip,jphilipsen05/zulip,souravbadami/zulip,AZtheAsian/zulip,mohsenSy/zulip,arpith/zulip,reyha/zulip,showell/zulip,sonali0901/zulip,amyliu345/zulip,krtkmj/zulip,Frouk/zulip,timabbott/zulip,PhilSk/zulip,calvinleenyc/zulip,amanharitsh123/zulip,Frouk/zulip,joyhchen/zulip,TigorC/zulip,umkay/zulip,TigorC/zulip,mahim97/zulip,sonali0901/zulip,synicalsyntax/zulip,shubhamdhama/zulip,KingxBanana/zulip,christi3k/zulip,jackrzhang/zulip,tommyip/zulip,brainwane/zulip,vabs22/zulip,mahim97/zulip,hackerkid/zulip,tommyip/zulip,krtkmj/zulip,christi3k/zulip,jrowan/zulip,andersk/zulip,SmartPeople/zulip,eeshangarg/zulip,aakash-cr7/zulip,KingxBanana/zulip,calvinleenyc/zulip,rht/zulip,verma-varsha/zulip,kou/zulip,cosmicAsymmetry/zulip,Jianchun1/zulip,andersk/zulip,punchagan/zulip,hackerkid/zulip,joyhchen/zulip,Vallher/zulip,niftynei/zulip,rishig/zulip,andersk/zulip,blaze225/zulip,vaidap/zulip,shubhamdhama/zulip,souravbadami/zulip,zulip/zulip,dattatreya303/zulip,brockwhittaker/zulip,krtkmj/zulip,dhcrzf/zulip,vaidap/zulip,JPJPJPOPOP/zulip,vikas-parashar/zulip,vabs22/zulip,vaidap/zulip,tommyip/zulip,KingxBanana/zulip,reyha/zulip,AZtheAsian/zulip,kou/zulip,hackerkid/zulip,Vallher/zulip,grave-w-grave/zulip,Vallher/zulip,samatdav/zulip,hackerkid/zulip,dawran6/zulip,grave-w-grave/zulip,Juanvulcano/zulip,sup95/zulip,brainwane/zulip,timabbott/zulip,sharmaeklavya2/zulip,zacps/zulip,niftynei/zulip,Frouk/zulip,Galexrt/zulip,rishig/zulip,zacps/zulip,dhcrzf/zulip,peiwei/zulip,showell/zulip,susansls/zulip,sup95/zulip,TigorC/zulip,timabbott/zulip,reyha/zulip,samatdav/zulip,zulip/zulip,andersk/zulip,showell/zulip,grave-w-grave/zulip,peguin40/zulip,samatdav/zulip,kou/zulip,cosmicAsymmetry/zulip,sonali0901/zulip,krtkmj/zulip,jrowan/zulip,amanharitsh123/zulip,JPJPJPOPOP/zulip,zacps/zulip,isht3/zulip,sonali0901/zulip,christi3k/zulip,aakash-cr7/zulip,samatdav/zulip,christi3k/zulip,peiwei/zulip,amanharitsh123/zulip,dattatreya303/zulip,eeshangarg/zulip,brockwhittaker/zulip,PhilSk/zulip,ryanbackman/zulip,sharmaeklavya2/zulip,amanharitsh123/zulip,brockwhittaker/zulip,kou/zulip,amyliu345/zulip,ahmadassaf/zulip,mohsenSy/zulip,krtkmj/zulip,Vallher/zulip,Jianchun1/zulip,reyha/zulip,umkay/zulip,SmartPeople/zulip,punchagan/zulip,amanharitsh123/zulip,Diptanshu8/zulip,AZtheAsian/zulip,jphilipsen05/zulip,punchagan/zulip,j831/zulip,ryanbackman/zulip,showell/zulip,jainayush975/zulip,blaze225/zulip,PhilSk/zulip,JPJPJPOPOP/zulip,jackrzhang/zulip,arpith/zulip,verma-varsha/zulip,Diptanshu8/zulip,PhilSk/zulip,jphilipsen05/zulip,umkay/zulip,zulip/zulip,dattatreya303/zulip,rishig/zulip,mohsenSy/zulip,zacps/zulip,JPJPJPOPOP/zulip,j831/zulip,paxapy/zulip,timabbott/zulip,umkay/zulip,cosmicAsymmetry/zulip,Juanvulcano/zulip,j831/zulip,ahmadassaf/zulip,jackrzhang/zulip,rht/zulip,aakash-cr7/zulip,niftynei/zulip,arpith/zulip,hackerkid/zulip,grave-w-grave/zulip,jrowan/zulip,peguin40/zulip,ryanbackman/zulip,calvinleenyc/zulip,jphilipsen05/zulip,ahmadassaf/zulip,krtkmj/zulip,calvinleenyc/zulip,grave-w-grave/zulip,KingxBanana/zulip,amyliu345/zulip,ryanbackman/zulip,brockwhittaker/zulip,Frouk/zulip,TigorC/zulip,shubhamdhama/zulip,mohsenSy/zulip,showell/zulip,sonali0901/zulip,eeshangarg/zulip,verma-varsha/zulip,vabs22/zulip,umkay/zulip,mohsenSy/zulip,jainayush975/zulip,peguin40/zulip,dawran6/zulip,reyha/zulip,ahmadassaf/zulip,cosmicAsymmetry/zulip,dawran6/zulip,synicalsyntax/zulip,tommyip/zulip,sup95/zulip,vikas-parashar/zulip,arpith/zulip,Diptanshu8/zulip,kou/zulip,brainwane/zulip,Frouk/zulip,verma-varsha/zulip,eeshangarg/zulip,jackrzhang/zulip,souravbadami/zulip,joyhchen/zulip,peiwei/zulip,sharmaeklavya2/zulip,sharmaeklavya2/zulip,synicalsyntax/zulip,souravbadami/zulip,krtkmj/zulip,paxapy/zulip,joyhchen/zulip,vikas-parashar/zulip,zulip/zulip,blaze225/zulip,blaze225/zulip,Jianchun1/zulip,amyliu345/zulip,jackrzhang/zulip,jrowan/zulip,vabs22/zulip,andersk/zulip,isht3/zulip,verma-varsha/zulip,Frouk/zulip,sonali0901/zulip,dawran6/zulip,amyliu345/zulip,grave-w-grave/zulip,AZtheAsian/zulip,vikas-parashar/zulip,arpith/zulip,vikas-parashar/zulip,reyha/zulip,niftynei/zulip,zulip/zulip,punchagan/zulip,hackerkid/zulip,rht/zulip,Vallher/zulip,ryanbackman/zulip,brockwhittaker/zulip,shubhamdhama/zulip,dhcrzf/zulip,tommyip/zulip,Jianchun1/zulip,susansls/zulip,Galexrt/zulip,arpith/zulip,zulip/zulip,Frouk/zulip,eeshangarg/zulip,synicalsyntax/zulip,vaidap/zulip,KingxBanana/zulip,mahim97/zulip,sharmaeklavya2/zulip,shubhamdhama/zulip,zulip/zulip,rht/zulip,isht3/zulip,jphilipsen05/zulip,ahmadassaf/zulip,amyliu345/zulip,SmartPeople/zulip,vaidap/zulip,mahim97/zulip,TigorC/zulip,jackrzhang/zulip,dhcrzf/zulip,calvinleenyc/zulip,Galexrt/zulip,paxapy/zulip,shubhamdhama/zulip,calvinleenyc/zulip,susansls/zulip,eeshangarg/zulip,jphilipsen05/zulip,ahmadassaf/zulip,sup95/zulip,cosmicAsymmetry/zulip,christi3k/zulip,punchagan/zulip,umkay/zulip,JPJPJPOPOP/zulip,paxapy/zulip,shubhamdhama/zulip,showell/zulip