Fix segfault when not setting a region on distrib model
Fix segfault when not setting a region on distrib model

MengjiaoH/ospray,MengjiaoH/ospray,MengjiaoH/ospray,wilsonCernWq/ospray,ospray/OSPRay,ospray/OSPRay,ospray/OSPRay,wilsonCernWq/ospray,MengjiaoH/ospray,MengjiaoH/ospray,wilsonCernWq/ospray,ospray/OSPRay