ENH:Added some error message on some error checking spots.
ENH:Added some error message on some error checking spots.

sankhesh/VTK,mspark93/VTK,naucoin/VTKSlicerWidgets,cjh1/VTK,aashish24/VTK-old,mspark93/VTK,demarle/VTK,naucoin/VTKSlicerWidgets,spthaolt/VTK,aashish24/VTK-old,mspark93/VTK,arnaudgelas/VTK,ashray/VTK-EVM,demarle/VTK,daviddoria/PointGraphsPhase1,jmerkow/VTK,SimVascular/VTK,demarle/VTK,johnkit/vtk-dev,msmolens/VTK,hendradarwin/VTK,gram526/VTK,jmerkow/VTK,hendradarwin/VTK,sumedhasingla/VTK,candy7393/VTK,msmolens/VTK,sumedhasingla/VTK,johnkit/vtk-dev,johnkit/vtk-dev,jeffbaumes/jeffbaumes-vtk,ashray/VTK-EVM,biddisco/VTK,cjh1/VTK,hendradarwin/VTK,candy7393/VTK,candy7393/VTK,demarle/VTK,spthaolt/VTK,johnkit/vtk-dev,Wuteyan/VTK,candy7393/VTK,cjh1/VTK,keithroe/vtkoptix,demarle/VTK,gram526/VTK,daviddoria/PointGraphsPhase1,SimVascular/VTK,SimVascular/VTK,jmerkow/VTK,jmerkow/VTK,collects/VTK,spthaolt/VTK,Wuteyan/VTK,sumedhasingla/VTK,keithroe/vtkoptix,Wuteyan/VTK,berendkleinhaneveld/VTK,arnaudgelas/VTK,ashray/VTK-EVM,hendradarwin/VTK,jmerkow/VTK,mspark93/VTK,johnkit/vtk-dev,ashray/VTK-EVM,mspark93/VTK,gram526/VTK,ashray/VTK-EVM,sumedhasingla/VTK,Wuteyan/VTK,daviddoria/PointGraphsPhase1,aashish24/VTK-old,collects/VTK,keithroe/vtkoptix,msmolens/VTK,spthaolt/VTK,sankhesh/VTK,berendkleinhaneveld/VTK,biddisco/VTK,collects/VTK,candy7393/VTK,biddisco/VTK,gram526/VTK,spthaolt/VTK,Wuteyan/VTK,arnaudgelas/VTK,berendkleinhaneveld/VTK,aashish24/VTK-old,cjh1/VTK,demarle/VTK,sankhesh/VTK,SimVascular/VTK,mspark93/VTK,demarle/VTK,arnaudgelas/VTK,candy7393/VTK,sankhesh/VTK,berendkleinhaneveld/VTK,msmolens/VTK,ashray/VTK-EVM,jeffbaumes/jeffbaumes-vtk,sumedhasingla/VTK,spthaolt/VTK,cjh1/VTK,naucoin/VTKSlicerWidgets,sumedhasingla/VTK,sankhesh/VTK,ashray/VTK-EVM,berendkleinhaneveld/VTK,naucoin/VTKSlicerWidgets,naucoin/VTKSlicerWidgets,ashray/VTK-EVM,sankhesh/VTK,hendradarwin/VTK,collects/VTK,biddisco/VTK,gram526/VTK,candy7393/VTK,biddisco/VTK,naucoin/VTKSlicerWidgets,SimVascular/VTK,demarle/VTK,arnaudgelas/VTK,daviddoria/PointGraphsPhase1,jmerkow/VTK,hendradarwin/VTK,jeffbaumes/jeffbaumes-vtk,keithroe/vtkoptix,mspark93/VTK,aashish24/VTK-old,collects/VTK,candy7393/VTK,daviddoria/PointGraphsPhase1,biddisco/VTK,berendkleinhaneveld/VTK,keithroe/vtkoptix,jmerkow/VTK,spthaolt/VTK,aashish24/VTK-old,msmolens/VTK,msmolens/VTK,jmerkow/VTK,mspark93/VTK,jeffbaumes/jeffbaumes-vtk,keithroe/vtkoptix,Wuteyan/VTK,gram526/VTK,Wuteyan/VTK,cjh1/VTK,daviddoria/PointGraphsPhase1,collects/VTK,arnaudgelas/VTK,gram526/VTK,SimVascular/VTK,berendkleinhaneveld/VTK,jeffbaumes/jeffbaumes-vtk,sankhesh/VTK,hendradarwin/VTK,keithroe/vtkoptix,sumedhasingla/VTK,gram526/VTK,sankhesh/VTK,msmolens/VTK,johnkit/vtk-dev,SimVascular/VTK,biddisco/VTK,SimVascular/VTK,jeffbaumes/jeffbaumes-vtk,msmolens/VTK,johnkit/vtk-dev,sumedhasingla/VTK,keithroe/vtkoptix