ReferenceError

@the1laz typeof does work? In some earlier builds it didn't, but I fixed it.

In 1v80 you don't get an error if you've not used something before. For instance:

setInterval(function() {
  print(i++);
}, 1000);

Will just print NaN I think? Not good.

I'm pretty confident now that in pretty much all cases (apart from the careful on=!on; example code I used to use) the ReferenceError will actually help to point out code that was in error (like Serial1.setup(...,{parity:even});, so hopefully it won't annoy people too much!