System.InvalidOperationException'在System.Drawing.dll中发生，

我正在用c#制作一个带有3,2,1倒计时的简单相机，使用Windows窗体打开一个新窗体来显示捕获的图像。当第一个Form空闲运行时，它最终会报错:"类型'System '的异常。InvalidOperationException'在System.Drawing.dll中发生，但未在用户代码中处理' .

程序显示错误是pictureBox1。图片正在其他地方使用:

pictureBox1.Image = (Bitmap)eventArgs.Frame.Clone();

我不确定是什么原因造成的。以下是与相机相关的所有代码:

    private static object locker = new Object();
    private FilterInfoCollection CaptureDevice;
    private VideoCaptureDevice FinalFrame;
    public Image File { get; private set; }
    public void Form1_Load(object sender, EventArgs e)
    {
        FormBorderStyle = FormBorderStyle.None;
        if (CaptureDevice == null)
        {
            lock (locker)
            {
                CaptureDevice = new FilterInfoCollection(FilterCategory.VideoInputDevice);
            }
        }
        foreach (FilterInfo Device in CaptureDevice)
        {
            lock(locker)
            { 
            comboBox1.Items.Add(Device.Name);
        }
            }
        lock (locker)
        {
            comboBox1.SelectedIndex = 0;
            FinalFrame = new VideoCaptureDevice();
            button1.PerformClick();
            button2.BringToFront();
        }
    }
    private void button1_Click(object sender, EventArgs e)
   {
        lock (locker)
        {
            button1.SendToBack();
            FinalFrame = new VideoCaptureDevice(CaptureDevice[comboBox1.SelectedIndex].MonikerString);
            FinalFrame.NewFrame += new NewFrameEventHandler(FinalFrame_NewFrame);
            FinalFrame.Start();
        }

    }
    private void FinalFrame_NewFrame(object sender, NewFrameEventArgs eventArgs)
    {
        lock (locker)
        {
            try
            {
                pictureBox1.Image = (Bitmap)eventArgs.Frame.Clone(); // <- Here is where the program indicates there is an error
            }
            catch (Exception exec)
            {
                Console.Write(exec);
           }
        }
    }
    private void Form1_FormClosing(object sender, FormClosingEventArgs e)
    {
        if (FinalFrame.IsRunning == true)
       {
           FinalFrame.Stop();
      }
    }
    private async void button2_Click(object sender, EventArgs e)
    {
        button2.SendToBack();
        button2.Hide();
        customLabel1.Show();
        await Task.Delay(200);
        customLabel1.BringToFront();
        customLabel1.Refresh();
        await Task.Delay(800);
        customLabel1.Refresh();
        customLabel1.Text = "2";
        await Task.Delay(800);
        customLabel1.Refresh();
        customLabel1.Text = "1";
        await Task.Delay(800);
        customLabel1.Refresh();
        customLabel1.Text = "3";
        customLabel1.Hide();
        button2.Show();
        button2.BringToFront();
        button2.Text = "CAPTURE";
        Form2 myPic = new Form2();
        myPic.pictureBox1.Image = (Bitmap)pictureBox1.Image.Clone() as Image;
        myPic.ShowDialog();
    }

//if (pictureBox1.Image != null)
pictureBox1.Image.Dispose();
pictureBox1.Image = (Bitmap)eventArgs.Frame.Clone();

void SetImageThreadSafe(PictureBox pb, Image img)
{
    if (pb.InvokeRequired)
    {
        BeginInvoke((Action) delegate
        {
            SetImageThreadSafe(pb, img);
        });
        return;
    }
    pb.Image?.Dispose();
    pb.Image = img;
}