Read the code and actually fix the nullptr problem.
Read the code and actually fix the nullptr problem.

.. instead of just blindly guessing..


git-svn-id: 353be9ac11a1e711854a13efcc2fc17d9d6b83e7@1834 c36c8488-0289-0348-9b64-b301f74bd9a7

BlueBrain/Tuvok,BlueBrain/Tuvok,BlueBrain/Tuvok