Meson

nixd/lib/Controller: use `CheckReturn` to simplify early-returns (NFC… #3261

Job	Run time
nix-build-develop-clang (none, release, true)	2m 54s
nix-build-develop-clang (none, release, false)	2m 55s
nix-build-develop-clang (none, debug, true)	2m 42s
nix-build-develop-clang (none, debug, false)	2m 46s
nix-build-develop-gcc (none, release, true)	2m 53s
nix-build-develop-gcc (none, release, false)	3m 9s
nix-build-develop-gcc (none, debug, true)	2m 57s
nix-build-develop-gcc (none, debug, false)	3m 0s
nix-build-develop-gcc (address, release, true)	4m 49s
nix-build-develop-gcc (address, release, false)	4m 47s
nix-build-develop-gcc (address, debug, true)	4m 2s
nix-build-develop-gcc (address, debug, false)	3m 55s
nix-build-develop-gcc (undefined, release, true)	4m 3s
nix-build-develop-gcc (undefined, release, false)	4m 14s
nix-build-develop-gcc (undefined, debug, true)	3m 16s
nix-build-develop-gcc (undefined, debug, false)	3m 20s
	55m 42s

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