array[array.length()] is nonsense if the array is empty.

You should prefer a language, like Rust, in which [T]::last is Option<&T> -- that is, we can ask for a reference to the last item, but there might not be one and so we're encouraged to do something about that.

IMNSHO The pit of success you're looking for is best dug with such features and not via fiddling with the index scheme.