Fix NAN bug when MLT propose a path with 0 radiance #707

Job	Run time
GPU Build Only (ubuntu-20.04, CUDA 11.7.0, optix-7.5.0)	1s
GPU Build Only (windows-latest, CUDA 11.7.0, optix-7.5.0)	3m 50s
GPU Build Only (ubuntu-20.04, CUDA 12.1.0, optix-7.5.0)	1m 22s
GPU Build Only (windows-latest, CUDA 12.1.0, optix-7.5.0)	3m 59s
GPU Build Only (ubuntu-20.04, CUDA 12.2.2, optix-7.5.0)	1s
GPU Build Only (windows-latest, CUDA 12.2.2, optix-7.5.0)	3m 51s
GPU Build Only (ubuntu-20.04, CUDA 12.3.2, optix-7.5.0)	1m 36s
GPU Build Only (windows-latest, CUDA 12.3.2, optix-7.5.0)	1s
GPU Build Only (ubuntu-20.04, CUDA 11.7.0, optix-7.7.0)	1m 22s
GPU Build Only (windows-latest, CUDA 11.7.0, optix-7.7.0)	1s
GPU Build Only (ubuntu-20.04, CUDA 12.1.0, optix-7.7.0)	1m 40s
GPU Build Only (windows-latest, CUDA 12.1.0, optix-7.7.0)	3m 8s
GPU Build Only (ubuntu-20.04, CUDA 12.2.2, optix-7.7.0)	1m 38s
GPU Build Only (windows-latest, CUDA 12.2.2, optix-7.7.0)	3m 53s
GPU Build Only (ubuntu-20.04, CUDA 12.3.2, optix-7.7.0)	1m 34s
GPU Build Only (windows-latest, CUDA 12.3.2, optix-7.7.0)	3m 49s
GPU Build Only (ubuntu-20.04, CUDA 11.7.0, optix-8.0.0)	1m 50s
GPU Build Only (windows-latest, CUDA 11.7.0, optix-8.0.0)	2m 33s
GPU Build Only (ubuntu-20.04, CUDA 12.1.0, optix-8.0.0)	1m 25s
GPU Build Only (windows-latest, CUDA 12.1.0, optix-8.0.0)	3m 9s
GPU Build Only (ubuntu-20.04, CUDA 12.2.2, optix-8.0.0)	1m 33s
GPU Build Only (windows-latest, CUDA 12.2.2, optix-8.0.0)	3m 56s
GPU Build Only (ubuntu-20.04, CUDA 12.3.2, optix-8.0.0)	1m 24s
GPU Build Only (windows-latest, CUDA 12.3.2, optix-8.0.0)	3m 15s
	50m 51s

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