Fix #74; envVarsPrefix app file name when not set #399

Job	Run time
build / windows-amd64 (Nim version-2-0)	6m 18s
build / windows-amd64 (Nim devel)	6m 51s
build / linux-amd64 (Nim version-1-6)	2m 8s
build / linux-gcc-14-amd64 (Nim version-2-0)	3m 48s
build / linux-gcc-14-amd64 (Nim version-1-6)	2m 17s
build / linux-amd64 (Nim devel)	4m 38s
build / windows-amd64 (Nim version-2-2)	5m 40s
build / linux-amd64 (Nim version-2-0)	3m 47s
build / linux-gcc-14-amd64 (Nim version-2-2)	3m 47s
build / linux-gcc-14-amd64 (Nim devel)	3m 52s
build / macos-arm64 (Nim version-2-0)	3m 52s
build / linux-i386 (Nim devel)	5m 48s
build / macos-amd64 (Nim version-2-2)	8m 6s
build / macos-arm64 (Nim version-2-2)	4m 5s
build / macos-amd64 (Nim devel)	6m 45s
build / macos-arm64 (Nim version-1-6)	3m 1s
build / macos-amd64 (Nim version-2-0)	7m 50s
build / macos-arm64 (Nim devel)	4m 20s
build / linux-i386 (Nim version-2-2)	5m 3s
build / linux-amd64 (Nim version-2-2)	3m 42s
build / macos-amd64 (Nim version-1-6)	3m 36s
build / windows-amd64 (Nim version-1-6)	4m 1s
build / linux-i386 (Nim version-1-6)	2m 50s
build / linux-i386 (Nim version-2-0)	4m 42s
	1h 50m 47s

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