Fix Bug 1134718: JS typeerror
Fix Bug 1134718: JS typeerror

Now checks button exists before trying to act on it.

whip112/Whip112,ronakkhunt/kuma,surajssd/kuma,whip112/Whip112,robhudson/kuma,groovecoder/kuma,varunkamra/kuma,chirilo/kuma,openjck/kuma,YOTOV-LIMITED/kuma,davehunt/kuma,a2sheppy/kuma,hoosteeno/kuma,RanadeepPolavarapu/kuma,cindyyu/kuma,Elchi3/kuma,RanadeepPolavarapu/kuma,yfdyh000/kuma,RanadeepPolavarapu/kuma,whip112/Whip112,hoosteeno/kuma,MenZil/kuma,darkwing/kuma,chirilo/kuma,anaran/kuma,surajssd/kuma,ronakkhunt/kuma,SphinxKnight/kuma,jwhitlock/kuma,SphinxKnight/kuma,jgmize/kuma,ronakkhunt/kuma,safwanrahman/kuma,jwhitlock/kuma,jezdez/kuma,biswajitsahu/kuma,surajssd/kuma,Elchi3/kuma,YOTOV-LIMITED/kuma,escattone/kuma,carnell69/kuma,yfdyh000/kuma,FrankBian/kuma,chirilo/kuma,surajssd/kuma,yfdyh000/kuma,YOTOV-LIMITED/kuma,hoosteeno/kuma,safwanrahman/kuma,nhenezi/kuma,yfdyh000/kuma,hoosteeno/kuma,davidyezsetz/kuma,biswajitsahu/kuma,MenZil/kuma,scrollback/kuma,davehunt/kuma,darkwing/kuma,utkbansal/kuma,tximikel/kuma,utkbansal/kuma,varunkamra/kuma,cindyyu/kuma,jezdez/kuma,chirilo/kuma,surajssd/kuma,cindyyu/kuma,nhenezi/kuma,MenZil/kuma,biswajitsahu/kuma,bluemini/kuma,openjck/kuma,ollie314/kuma,robhudson/kuma,darkwing/kuma,utkbansal/kuma,whip112/Whip112,surajssd/kuma,safwanrahman/kuma,escattone/kuma,davehunt/kuma,davidyezsetz/kuma,bluemini/kuma,openjck/kuma,jgmize/kuma,hoosteeno/kuma,jezdez/kuma,biswajitsahu/kuma,davidyezsetz/kuma,safwanrahman/kuma,jgmize/kuma,SphinxKnight/kuma,Elchi3/kuma,whip112/Whip112,scrollback/kuma,utkbansal/kuma,a2sheppy/kuma,a2sheppy/kuma,yfdyh000/kuma,jgmize/kuma,biswajitsahu/kuma,cindyyu/kuma,whip112/Whip112,FrankBian/kuma,openjck/kuma,bluemini/kuma,escattone/kuma,carnell69/kuma,MenZil/kuma,MenZil/kuma,robhudson/kuma,anaran/kuma,varunkamra/kuma,ronakkhunt/kuma,scrollback/kuma,groovecoder/kuma,a2sheppy/kuma,Elchi3/kuma,darkwing/kuma,tximikel/kuma,YOTOV-LIMITED/kuma,utkbansal/kuma,carnell69/kuma,anaran/kuma,robhudson/kuma,YOTOV-LIMITED/kuma,MenZil/kuma,ronakkhunt/kuma,robhudson/kuma,chirilo/kuma,groovecoder/kuma,utkbansal/kuma,openjck/kuma,FrankBian/kuma,chirilo/kuma,tximikel/kuma,scrollback/kuma,SphinxKnight/kuma,tximikel/kuma,carnell69/kuma,bluemini/kuma,biswajitsahu/kuma,jezdez/kuma,RanadeepPolavarapu/kuma,ollie314/kuma,FrankBian/kuma,jgmize/kuma,ronakkhunt/kuma,robhudson/kuma,carnell69/kuma,nhenezi/kuma,davehunt/kuma,nhenezi/kuma,mozilla/kuma,FrankBian/kuma,anaran/kuma,groovecoder/kuma,scrollback/kuma,hoosteeno/kuma,cindyyu/kuma,varunkamra/kuma,tximikel/kuma,varunkamra/kuma,nhenezi/kuma,SphinxKnight/kuma,bluemini/kuma,safwanrahman/kuma,anaran/kuma,ollie314/kuma,Elchi3/kuma,jwhitlock/kuma,a2sheppy/kuma,jezdez/kuma,SphinxKnight/kuma,groovecoder/kuma,RanadeepPolavarapu/kuma,groovecoder/kuma,mozilla/kuma,openjck/kuma,mozilla/kuma,ollie314/kuma,davehunt/kuma,davidyezsetz/kuma,jwhitlock/kuma,darkwing/kuma,davehunt/kuma,cindyyu/kuma,bluemini/kuma,mozilla/kuma,YOTOV-LIMITED/kuma,varunkamra/kuma,ollie314/kuma,jgmize/kuma,jezdez/kuma,davidyezsetz/kuma,anaran/kuma,mozilla/kuma,ollie314/kuma,safwanrahman/kuma,yfdyh000/kuma,tximikel/kuma,carnell69/kuma,jwhitlock/kuma,darkwing/kuma,RanadeepPolavarapu/kuma