proper error handling?

Probably the best idea is to use the hardware watchdog - that's what they have them built in for: https://www.espruino.com/Reference#l_E_enableWatchdog

So:

E.enableWatchdog(10, false);
setInterval(function() {
   // your code here
    E.kickWatchdog();
}, 2000);

If the function doesn't complete to the point that kickWatchdog is called, the whole device will restart.

But you might also want to look at https://www.espruino.com/Debugger#debugging-when-not-connected - at least then when it stops working you can maybe connect and get some idea what happened?