Newbi init and stops working after a while

The code "works" ie it give me some nice LED's
The problem is, it stops working after a time.

// our main function
function puckLeds(){
  let leds= 0;
  let timerId = null;

  digitalWrite([LED3,LED2,LED1], leds);

  // watch for the Big Red Button
  setWatch(function() {
    if ( timerId !== null){
      clearTimeout(timerId);
    } 
    leds = (leds + 1)%7;
    digitalWrite([LED3,LED2,LED1], leds);
    timerId = setTimeout(function () {
    digitalWrite([LED3,LED2,LED1], 0);
    }, 10000);
  }, BTN, {edge:"falling", debounce:100, repeat:true}); 
}

// ensure that the code is available after reload or whatever
E.on('init', function() {
  console.log("hello");
  puckLeds();
});

save();

Edit after input below.
Placement of pulldown did not seem to work
pinMode(BTN,"input_pulldown");

function puckLeds(){
  let leds= 0;
  let timerId = null;

  digitalWrite([LED3,LED2,LED1], leds);

  setWatch(function() {
    // pinMode(BTN,"input_pulldown");
    if ( timerId !== null){
      clearTimeout(timerId);
    } 
    leds = (leds + 1)%7;
    digitalWrite([LED3,LED2,LED1], leds);
    timerId = setTimeout(function () {
    digitalWrite([LED3,LED2,LED1], 0);
    }, 10000);
  }, BTN, {edge:"falling", debounce:100, repeat:true}); 
  pinMode(BTN,"input_pulldown");
}

E.on('init', function() {
  console.log("hello");
  puckLeds();
});

save();