Add a null check for the 3D texture created in the compositor demo.
Add a null check for the 3D texture created in the compositor demo.

RealityFactory/ogre,OGRECave/ogre,OGRECave/ogre,paroj/ogre,RealityFactory/ogre,paroj/ogre,RealityFactory/ogre,paroj/ogre,RealityFactory/ogre,paroj/ogre,OGRECave/ogre,RealityFactory/ogre,OGRECave/ogre,OGRECave/ogre,paroj/ogre