Generate error if a variable in output_variables doesn't exist
Generate error if a variable in output_variables doesn't exist

Ref #1905

r18282

nuclear-wizard/moose,bwspenc/moose,jbair34/moose,tonkmr/moose,liuwenf/moose,capitalaslash/moose,wgapl/moose,jessecarterMOOSE/moose,idaholab/moose,Chuban/moose,roystgnr/moose,zzyfisherman/moose,apc-llc/moose,raghavaggarwal/moose,SudiptaBiswas/moose,backmari/moose,markr622/moose,kasra83/moose,sapitts/moose,jasondhales/moose,milljm/moose,xy515258/moose,WilkAndy/moose,shanestafford/moose,sapitts/moose,wgapl/moose,bwspenc/moose,SudiptaBiswas/moose,kasra83/moose,raghavaggarwal/moose,adamLange/moose,cpritam/moose,joshua-cogliati-inl/moose,raghavaggarwal/moose,roystgnr/moose,YaqiWang/moose,joshua-cogliati-inl/moose,giopastor/moose,jinmm1992/moose,sapitts/moose,idaholab/moose,bwspenc/moose,capitalaslash/moose,bwspenc/moose,shanestafford/moose,apc-llc/moose,jinmm1992/moose,roystgnr/moose,jbair34/moose,milljm/moose,zzyfisherman/moose,jessecarterMOOSE/moose,wgapl/moose,kasra83/moose,andrsd/moose,jessecarterMOOSE/moose,harterj/moose,zzyfisherman/moose,harterj/moose,danielru/moose,yipenggao/moose,waxmanr/moose,friedmud/moose,milljm/moose,liuwenf/moose,WilkAndy/moose,roystgnr/moose,friedmud/moose,stimpsonsg/moose,adamLange/moose,mellis13/moose,nuclear-wizard/moose,lindsayad/moose,tonkmr/moose,harterj/moose,stimpsonsg/moose,apc-llc/moose,lindsayad/moose,zzyfisherman/moose,cpritam/moose,jessecarterMOOSE/moose,milljm/moose,giopastor/moose,andrsd/moose,Chuban/moose,liuwenf/moose,backmari/moose,yipenggao/moose,xy515258/moose,harterj/moose,giopastor/moose,waxmanr/moose,jasondhales/moose,zzyfisherman/moose,jhbradley/moose,joshua-cogliati-inl/moose,laagesen/moose,raghavaggarwal/moose,WilkAndy/moose,mellis13/moose,idaholab/moose,stimpsonsg/moose,jhbradley/moose,katyhuff/moose,markr622/moose,roystgnr/moose,WilkAndy/moose,jiangwen84/moose,dschwen/moose,bwspenc/moose,laagesen/moose,WilkAndy/moose,WilkAndy/moose,nuclear-wizard/moose,sapitts/moose,wgapl/moose,YaqiWang/moose,dschwen/moose,backmari/moose,tonkmr/moose,SudiptaBiswas/moose,YaqiWang/moose,jinmm1992/moose,cpritam/moose,adamLange/moose,liuwenf/moose,lindsayad/moose,lindsayad/moose,shanestafford/moose,zzyfisherman/moose,permcody/moose,markr622/moose,liuwenf/moose,shanestafford/moose,markr622/moose,danielru/moose,mellis13/moose,laagesen/moose,tonkmr/moose,joshua-cogliati-inl/moose,danielru/moose,jasondhales/moose,capitalaslash/moose,sapitts/moose,jiangwen84/moose,laagesen/moose,shanestafford/moose,andrsd/moose,friedmud/moose,jiangwen84/moose,giopastor/moose,cpritam/moose,Chuban/moose,apc-llc/moose,andrsd/moose,yipenggao/moose,katyhuff/moose,cpritam/moose,jessecarterMOOSE/moose,roystgnr/moose,andrsd/moose,permcody/moose,jhbradley/moose,mellis13/moose,idaholab/moose,dschwen/moose,SudiptaBiswas/moose,jinmm1992/moose,harterj/moose,idaholab/moose,YaqiWang/moose,katyhuff/moose,jiangwen84/moose,yipenggao/moose,laagesen/moose,kasra83/moose,xy515258/moose,roystgnr/moose,jhbradley/moose,shanestafford/moose,waxmanr/moose,SudiptaBiswas/moose,jasondhales/moose,permcody/moose,xy515258/moose,lindsayad/moose,permcody/moose,waxmanr/moose,jbair34/moose,capitalaslash/moose,adamLange/moose,katyhuff/moose,liuwenf/moose,tonkmr/moose,Chuban/moose,milljm/moose,dschwen/moose,nuclear-wizard/moose,backmari/moose,stimpsonsg/moose,danielru/moose,friedmud/moose,jbair34/moose,cpritam/moose,tonkmr/moose,dschwen/moose