void jswrap_graphics_drawCircle(JsVar *parent, int x, int y, int rad) {
  JsGraphics gfx; if (!graphicsGetFromVar(&gfx, parent)) return;
  graphicsDrawCircle(&gfx, (short)x,(short)y,(short)rad);
  graphicsSetVar(&gfx); // gfx data changed because modified area
}

The product reads data past the end, or before the beginning, of the intended buffer.