Fixed script warnings


git-svn-id: http://svn.openscenegraph.org/osg/OpenSceneGraph/trunk@14623 16af8721-9629-0410-8352-f15c8da7e697
Added if () block to avoid script variables set to NOT-Found being used in searching


git-svn-id: http://svn.openscenegraph.org/osg/OpenSceneGraph/trunk@14624 16af8721-9629-0410-8352-f15c8da7e697