better error message when the mpi device cannot be created in ospInit()
better error message when the mpi device cannot be created in ospInit()

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