canvas008.tsx

 React.useEffect(() => {
    let mouseDown: boolean = false;
    ...

    return function cleanup() {
      if (canvasRef.current) {
        canvasRef.current.removeEventListener('mousedown', handleMouseDown);
        canvasRef.current.removeEventListener('mouseup', handleMouseUp);
        canvasRef.current.removeEventListener('mousemove', handleMouseMove);
      }
  }
 }, [context]);