Return a sane error if there is no Nodes with that name instead of IndexError
Return a sane error if there is no Nodes with that name instead of IndexError

dennybaa/st2contrib,pearsontechnology/st2contrib,pearsontechnology/st2contrib,pidah/st2contrib,lmEshoo/st2contrib,tonybaloney/st2contrib,digideskio/st2contrib,pearsontechnology/st2contrib,armab/st2contrib,StackStorm/st2contrib,StackStorm/st2contrib,pearsontechnology/st2contrib,dennybaa/st2contrib,pinterb/st2contrib,StackStorm/st2contrib,pidah/st2contrib,psychopenguin/st2contrib,armab/st2contrib,armab/st2contrib,meirwah/st2contrib,tonybaloney/st2contrib,meirwah/st2contrib,pinterb/st2contrib,psychopenguin/st2contrib,tonybaloney/st2contrib,digideskio/st2contrib,lmEshoo/st2contrib,pidah/st2contrib