Remove else from if constexpr when there are returns #5854

Job	Run time
CI-Rocm-HIP (hipcc, Release, hip, serial)	33m 6s
CI-Cuda-Host (g++, Release, cuda, serial)	39m 58s
CI-Rocm-HIP (hipcc, Release, hip, mpi)	33m 26s
CI-Cuda-Host (g++, Release, cuda, mpi)	41m 24s
CI-Rocm-HIP (hipcc, Debug, hip, serial)	53m 7s
CI-Cuda-Host (g++, Release, host, serial)	11m 35s
CI-Rocm-HIP (hipcc, Debug, hip, mpi)	55m 45s
CI-Cuda-Host (g++, Release, host, mpi)	12m 3s
CI-Cuda-Host (g++, Debug, cuda, serial)	1h 14m 16s
CI-Cuda-Host (g++, Debug, cuda, mpi)	1h 11m 36s
CI-Cuda-Host (g++, Debug, host, serial)	10m 18s
CI-Cuda-Host (g++, Debug, host, mpi)	10m 37s
CI-Cuda-Host (clang++-15, Release, cuda, serial)	27m 1s
CI-Cuda-Host (clang++-15, Release, cuda, mpi)	26m 24s
CI-Cuda-Host (clang++-15, Release, host, serial)	9m 50s
CI-Cuda-Host (clang++-15, Release, host, mpi)	9m 58s
CI-Cuda-Host (clang++-15, Debug, host, serial)	7m 39s
CI-Cuda-Host (clang++-15, Debug, host, mpi)	7m 38s
	8h 55m 41s

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