Meu código está bem diferente do original, em função das customizações que fiz. Mas não consigo entender porque a raquete do oponente desaparece quando insiro a chance de errar.

Consegui verificar que tem a ver com a variável da chance de errar, que eu chamei de "errorProbability". Quando eu a retiro, a raquete volta a se comportar normalmente, por exemplo.

Já alterei os nome, pois achei que poderiam ser algum nome de variável própria da plataforma e estaria em conflito, mas mesmo nomeando da forma como foi sugerida na aula o erro se mantem.

Link pro sketch https://editor.p5js.org/regisncoelho/sketches/XKgMKxBHK Código do jogo abaixo

let hit = false;

var xBall = 300;
var yBall = 200;
let dBall = 40;
let radius = dBall/2;

let speed = 8

let speedXBall = speed;
let speedYBall = speed;
let speedYPlayerTwo;

let xRacketOne = 5;
let yRacketOne = 250;
let wRacket = 15;
let hRacket = 120;

let xRacketTwo;
let yRacketTwo = 250;

let scorePlayerOne = 0;
let scorePlayerTwo = 0

let strike;
let point;
let soundtrack;

let errorProbability;

function preload() {
  soundtrack = loadSound("trilha.mp3");
  point = loadSound("point.mp3");
  strike = loadSound("strike.wav")
}

function setup() {
  createCanvas(windowWidth, windowHeight)
  // soundtrack.loop();
}

function draw() {
  let xRacketTwo = windowWidth-windowHeight/35;
  background('#2577AB');
  fill(255);
  stroke(0);
  rect((windowWidth/2) - 4, 0, 8, windowHeight);
  stroke(255);
  line (0, windowHeight/2, windowWidth, windowHeight/2);
  showBall();
  moveBall();
  checkTouchBorder();
  showRackets(xRacketOne, yRacketOne);
  moveRacketOne();
  checkTouchRackets(xRacketOne, yRacketOne);
  checkTouchRackets(xRacketTwo, yRacketTwo);
  showRackets(xRacketTwo, yRacketTwo);
  moveRacketTwo();
  showScores();
}

function windowResized() {
  resizeCanvas(windowWidth, windowHeight);
}

function showBall (){
  fill('#FFD75D');
  stroke(0);
  circle(xBall,yBall,dBall)
}

function moveBall() {
  xBall += speedXBall;
  yBall += speedYBall
}

function moveRacketTwo () {
    speedYPlayerTwo = yBall - yRacketTwo - hRacket/2 - 30;
    yRacketTwo += speedYPlayerTwo + errorProbability
    calculateError()
}

function checkTouchBorder() {
    if (xBall + radius > width) {
    speedXBall *= -1;
    scorePlayerOne += 1;
    point.play();
    } 

    if (xBall + radius < 0 ){
    speedXBall *= -1;
    scorePlayerTwo += 1;
    point.play();

}
    if (yBall + radius > height ||
     yBall - radius<  0){
    speedYBall *= -1;
  }
}

function showRackets(x, y){
  fill('#FD6864');
  rect (x, y, wRacket, hRacket, 20);
}

function moveRacketOne(){
  if (keyIsDown (UP_ARROW)) {
    if (yRacketOne > 0){
    yRacketOne -= 10;
    }
  }
    if (keyIsDown (DOWN_ARROW)) {
      if (yRacketOne + hRacket < height){
      yRacketOne += 10;
    }
  }
}

function checkTouchRackets(x, y) {
  hit = collideRectCircle(x, 
                          y, 
                          wRacket, 
                          hRacket, 
                          xBall, 
                          yBall, 
                          radius);

  if (hit){
    speedXBall *= -1;
    strike.play();
  }
}

function showScores() {
  // rect(windowWidth/2 - windowWidth/17, windowHeight/34, windowHeight/15, windowHeight/20)
  fill(255)
  textSize(25)
  textAlign(CENTER)
  noStroke();
  text (scorePlayerOne, windowWidth/2 - windowWidth/20, windowHeight/15)
  text (scorePlayerTwo, windowWidth/2 + windowWidth/22, windowHeight/15)
}

function calculateError() {
  if (scorePlayerTwo >= scorePlayerOne) {
    errorProbability += 1;
    if (errorProbability >= 39){
      errorProbability = 40
    }
  }
  else {
    errorProbability -= 1;
    if (errorProbability <= 35){
      errorProbability = 35
    }
  }
}