How do I fix the "Mixing "active" and "static" modes" error in my code in Processing?

Question

Java

Tell me how to fix the error?
Here is the code:

int size = 10;


void setup () {
  fullScreen();
  background(255);
}


int w = width / size;
int h = height / size;


Cell[][] world;



int[] random_genome () {
  int[] result = new int[64];
  for (int i = 0; i < 64; i++) {
    result[i] = int(random(64));
  }
  return result;
}

int[] empty_genome () {
  int[] result = new int[64];
  for (int i = 0; i < 64; i++) {
    result[i] = 63;
  }
  return result;
}





class Cell {
  int[] genome;
  int energy;
  boolean isCell;
  int[] rgb;
  Cell (int[] arg_genome, int arg_energy, boolean arg_isCell, int[] arg_rgb) {
    genome = arg_genome;
    energy = arg_energy;
    isCell = arg_isCell;
    rgb = arg_rgb;
  }
}





void createWorld () {
  for (int x = 0; x < w; x++) {
    for (int y = 0; y < h; y++) {
      if (random(100) < 10) {
        world[x][y] = new Cell(random_genome(), 500, true, new int[] {127, 127, 127});
      } else {
        world[x][y] = new Cell(empty_genome(), 0, false, new int[] {255, 255, 255});
      }
    }
  }
}

void drawWorld () {
  for (int x = 0; x < w; x++) {
    for (int y = 0; y < h; y++) {
      stroke(world[x][y].rgb[0], world[x][y].rgb[1], world[x][y].rgb[2]);
      point(x * size, y * size);
    }
  }
}


createWorld();
drawWorld();