FIX: safe when pointer is NULL


git-svn-id: https://www.nitrc.org/svn/cmtk/trunk@4920 42a5c34f-2066-0410-bec5-ba365beb4995
FIX: catch exception (Coverity defect)


git-svn-id: https://www.nitrc.org/svn/cmtk/trunk@4921 42a5c34f-2066-0410-bec5-ba365beb4995