fixed null deref warning
fixed null deref warning

fixed by bailing out instead of just calling vtkErrorMacro upon memory allocation failure.  Failure unlikely to ever happen anyway.

Change-Id: I479e47c61de33440a69cb42a0be619e150453c3e

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