Back button being weird on Bangle.js 1

Looks like that's it... This breaks on Bangle.js 1:

var mainmenu = {
  "" : { title : "-- Main Menu --", back : function() {} },
  "Hello" : function() { }
};
E.showMenu(mainmenu);

And this breaks on Bangle.js 1 and 2:

E.showScroller({
  h : 40, c : 8,
  draw : (idx, r) => {
    g.setBgColor((idx&1)?"#666":"#999").clea­rRect(r.x,r.y,r.x+r.w-1,r.y+r.h-1);
    g.setFont("6x8:2").drawString("Item Number\n"+idx,r.x+10,r.y+4);
  },
  select : (idx) => console.log("You selected ", idx),
  back : function() {}
});

It's from this PR https://github.com/espruino/Espruino/pul­l/2286 so it looks like while it was tested, it wasn't tested on Bangle.js 1, and unfortunately showScroller didn't get tested on either of them (although it should have been on Bangle.js 2 as part of showMenu).

I'll try and get a fix in now