Even if you are working in a compiled language, you still can't always rely on the compiler. The compiler will not stop a programmer from writing invalid code,

Even if you are working in a compiled language, you still can't always rely on the compiler. The compiler will not stop a programmer from writing invalid code, without any tests, and checking it into a repository, where it silently waits for an unsuspecting programmer to discover it months later.... "How do I do what I want here? Aha, someone already wrote ExactlyWhatIWantHere.... WTF, it doesn't even compile? But how is anyone using it? Oh, it's not being used anywhere? How the heck did it get here? Ugh..."