Swapping the order of these checks, which I guess is the most minimal
optimization possible
BenchmarkGetEnv-10 68764720 16.82 ns/op 0 B/op 0 allocs/op
BenchmarkMap-10 454135184 2.635 ns/op 0 B/op 0 allocs/op
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>