BUG: A valid, but empty, tree was making the adapter/view crash later. So also testing for an "empty" tree.
BUG: A valid, but empty, tree was making the adapter/view crash later. So also testing for an "empty" tree.

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