This can be fixed by:

       for (let re of rects) {
         push();
         translate(re.body.position.x, re.body.position.y);
         rotate(re.body.angle);
    -    rect(0, 0, re.w, re.h, 2);
    +    rect(0, 0, re.w - 1, re.h - 1, 2);
         pop();
       }