hue property is undefined in paper.js

I need to remove newCircle.fillColor = "red"; in order to get colors other than red but when i remove it, it says the property of hue is undefined.

var circles = [];


enter code here

function onKeyDown(event) {

var maxPoint = new Point(view.size.width, view.size.height);
var randomPoint = Point.random();
var point = maxPoint * randomPoint;
var newCircle = new Path.Circle(point,500)

if(event.key === "a"){
   bubbles.play();
   newCircle.fillColor = "#2c3e50";
   }

  else if(event.key === "b"){
  newCircle.fillColor = "#2c3e50";
  clay.play();
   }

  else if(event.key === "c"){
  newCircle.fillColor = "#00ff0f";
  confetti.play();
  }
  newCircle.fillColor = "red";
  circles.push(newCircle);
  }

 function onFrame(event){
 for(var i = 0; i < circles.length; i++){
  circles[i].fillColor.hue += 1;
  circles[i].scale(.9);
 }
 }