I don't like this idea. For me, trying to access an array element (or collection for that matter) with an out of bound index is a programmer error and should crash.
In rare cases and algorithms that this might make sense and end up being more readable, I may add a private extension to Array or Collection to take care of it. It is just a few lines of straightforward hard to screw-up code. I don't think such helper facility belongs in the standard library.