What does the expression “Fail Early” mean, and when would you want to do so?

Essentially, fail fast (a.k.a. fail early) is to code your software such that, when there is a problem, the software fails as soon as and as visibly as possible, rather than trying to proceed in a possibly unstable state.

Fail Fast approach won’t reduce the overall number of bugs, at least not at first, but it’ll make most defects much easier to find.