i recently wrote some code but no matter what, i keep receiving the message above.
here, what i wrote:

Paddle myPaddle;

void setup()
  {size(500, 500);
  myPaddle = new Paddle(0);  //======> this line apears highlighted when i click run button
  }

void draw()
  {background(0);
  myPaddle.display(); 
  }
 
class Paddle
  {
   boolean side;
 
 
  Paddle (boolean tempSide)
    {
     side = tempSide;
    }
 
  void display()
    {noStroke();
     fill(255);
     rectMode(CENTER);
     if(side==0) rect(25, mouseY, 50, 100);
     else rect(475, mouseY, 50, 100);
    }
  }