Possible bug with unknown args to function?

Parsing a variable of type "undefined" creates an error:

function foo(x, y) {
  for (var i=0; i<arguments.length; i++) {
     console.log("i="+i);
     try { console.log("val="+arguments[i]); } catch (e) { console.log(e);}
  }
}
foo(undefined, 1, undefined, 2)

i=0
ReferenceError: ReferenceError: "0" is not defined
i=1
val=1
i=2
ReferenceError: ReferenceError: "2" is not defined
i=3
val=2
=undefined

So there are two bugs: arguments.length is not updated (documented https://www.espruino.com/Reference#l__gl­obal_arguments). arguments fails for undefined arguments (not documented).