Check if the selection array exists before dereferencing it.
Check if the selection array exists before dereferencing it.

Change-Id: I63a6952a0d4493d57096d6b544f03ed9a6f0b107

hendradarwin/VTK,msmolens/VTK,sankhesh/VTK,candy7393/VTK,gram526/VTK,demarle/VTK,msmolens/VTK,demarle/VTK,SimVascular/VTK,candy7393/VTK,candy7393/VTK,sankhesh/VTK,sankhesh/VTK,SimVascular/VTK,keithroe/vtkoptix,msmolens/VTK,johnkit/vtk-dev,mspark93/VTK,jmerkow/VTK,keithroe/vtkoptix,johnkit/vtk-dev,ashray/VTK-EVM,ashray/VTK-EVM,sankhesh/VTK,ashray/VTK-EVM,sumedhasingla/VTK,mspark93/VTK,sumedhasingla/VTK,mspark93/VTK,hendradarwin/VTK,sumedhasingla/VTK,sankhesh/VTK,ashray/VTK-EVM,jmerkow/VTK,demarle/VTK,hendradarwin/VTK,ashray/VTK-EVM,jmerkow/VTK,mspark93/VTK,jmerkow/VTK,ashray/VTK-EVM,msmolens/VTK,demarle/VTK,mspark93/VTK,keithroe/vtkoptix,hendradarwin/VTK,jmerkow/VTK,jmerkow/VTK,candy7393/VTK,jmerkow/VTK,sankhesh/VTK,johnkit/vtk-dev,gram526/VTK,SimVascular/VTK,johnkit/vtk-dev,sumedhasingla/VTK,keithroe/vtkoptix,SimVascular/VTK,gram526/VTK,sankhesh/VTK,msmolens/VTK,gram526/VTK,mspark93/VTK,candy7393/VTK,gram526/VTK,johnkit/vtk-dev,gram526/VTK,hendradarwin/VTK,keithroe/vtkoptix,gram526/VTK,sumedhasingla/VTK,keithroe/vtkoptix,johnkit/vtk-dev,ashray/VTK-EVM,demarle/VTK,sumedhasingla/VTK,ashray/VTK-EVM,msmolens/VTK,johnkit/vtk-dev,sankhesh/VTK,demarle/VTK,keithroe/vtkoptix,mspark93/VTK,sumedhasingla/VTK,SimVascular/VTK,SimVascular/VTK,sumedhasingla/VTK,SimVascular/VTK,jmerkow/VTK,demarle/VTK,demarle/VTK,candy7393/VTK,candy7393/VTK,candy7393/VTK,msmolens/VTK,gram526/VTK,msmolens/VTK,keithroe/vtkoptix,hendradarwin/VTK,mspark93/VTK,hendradarwin/VTK,SimVascular/VTK