sml array indexing fail

pwn-smlnj.sml

(* Running `fail ()` at the repl will cause it to say:
   unexpected exception (bug?) in SML/NJ: Representation [Representation] *)
fun fail () =
    let fun idx a i =
            case (Array.sub (a, i))
             of NONE => raise Fail "owt"
              | SOME x => x
        val a = Array.array (1, SOME (42, 1337))
    in idx a 0 end


(* Running `thing (fail ())` will print some bogus numbers.
 * If I had thing *call* fail, then sml/nj crashed while compiling the file?? *)
fun thing x =
    let val (i, j) = x
    in print (Int.toString i ^ " " ^ Int.toString j ^ "\n") end