Visual Studio - C# 错误:System.Windows.Forms.dll 中发生类型为“System

调试程序并尝试关闭程序然后程序关闭时，我都会收到错误，并且我收到此错误An unhandled exception of type 'System.InvalidOperationException' occurred in System.Windows.Forms.dll

并向我展示我在代码中有一些错误。

我的代码：

void proc_OutputDataReceived(object sender, DataReceivedEventArgs e)
    {
        if (stop)
        {
            var proc = (Process)sender;
            stop = false; // allows you to spawn a new thread after stopping the first
            proc.SynchronizingObject = this; // puts the form in charge of async communication
            proc.Kill(); // terminates the thread
            proc.WaitForExit(); // thread is killed asynchronously, so this goes here...
        }
        if (e.Data != null)
        {
            string newLine = e.Data.Trim() + Environment.NewLine;
            MethodInvoker append = () => {
                pingInformatsioon.Text += newLine;
                if (checkBox1.Checked)
                {
                    WriteLog(newLine);
                }
            };
            pingInformatsioon.BeginInvoke(append);
        }
    }

总是出现黄色pingInformatsioon.BeginInvoke(append);好像有什么不对劲..