Summary: Can't figure out why I'm getting this Null Pointer Exception error.

I am new to Processing and to programming in general.  I am trying to model a concept in nonlinearity in statistics.  The concept is vicious cycles in success and failure, where one's chance for success in a win or lose event are higher if they were successful in the last event.  The math is simple; one's chances for winning in the next event are 75% if they won in the last event, otherwise it is 25%.  

I've built this into a class so I can visualize it.  Basically, an ellipse moves at a constant speed from left to right, incrementing vertically up 5 pixels for each success and down for each failure.  I want to make this work for one object, then add multiple objects to see what it looks like.

The logic is simple.  I created two arrays of 100 outcomes, one with 75 wins ( 1's) and 25 losses (0's) to reflect the probability of winning after a win, and the other for the probability of winning after a lose.  Then depending on whether the last event was a win or lose, I pick the appropriate array and randomly select an outcome to determine the result of the current event.  

In trying to reflect this is basic vector movement logic, I am getting a Null Pointer Exception error, with the player.update() method in draw being highlighted.

Code:

Player player;

void Setup() { 
  size(500,500);
  background(50);
  
  player = new Player();
}

void draw() {
  noStroke();
  
  player.update();
  player.checkEdges();
  player.display(); 
}
  
class Player {
  
  PVector location;
  PVector velocity;
  
  Player() {
    location = new PVector(0,height/2);
    velocity = new PVector(1,0);
  }
  
  void update() {
    /*create two sets of outcomes, one if the last event was a win, one   for it was a loss*/
    int[] winProbOutcomes = new int[100];  
    int[] loseProbOutcomes = new int[100];
    for (int i = 0; i < 100; i++) {
	if(i<=75) {
	  winProbOutcomes[i] = 1;
	}else{
	  winProbOutcomes[i]=0;
	}
    }
    for (int j = 0; j< 100; j++) {
	if (j<=25) {
	  loseProbOutcomes[j] = 1;
	}else{
	  loseProbOutcomes[j] = 0;
	}
    }
    //start from a random outcome for first event
    float lastEvent = random(2);
    //get an outcome from the set based on lastEvent
    int outcome;
    if(lastEvent == 1) {
	outcome = winProbOutcomes[int(random(100))];
    }else{
	outcome = loseProbOutcomes[int(random(100))];
    }
    //convert to vertical increment
    int increment;
    if (outcome == 1) {
	increment = 5;
    }else{
	increment = -5;
    }
    //set velocity.y to increment
    velocity.y = increment;
    
    location.add(velocity);
  }

 void display() {
    stroke(0);
    fill(175);
    ellipse(location.x,location.y,8,8);
  }

  void checkEdges() {

    if (location.x > width) {
	location.x = 0;
    }

    if (location.y > height) {
	location.y = 0;
    }  else if (location.y < 0) {
	location.y = height;
    }
  }
}