Function "" not found

Ok, great! Narrowed it down to:

//E.setFlags({pretokenise:0}) // this fixes it
function go() {
  Promise.resolve().then(function() {
    console.log("Ok");
  }).catch(function(e) {
    console.log("ERROR",e);
  });
}
go()

So it's to do with catch being converted to a token even though in this case it's just a function name. Just filed an issue: https://github.com/espruino/Espruino/issues/1868