如何从c#powershell脚本执行中提取$ lastexitcode

using System;
using System.Management.Automation;

namespace PowerShellExample
{
    class Program
    {
        static void Main(string[] args)
        {
            using (PowerShell powerShell = PowerShell.Create())
            {
                // 添加PowerShell脚本
                powerShell.AddScript("Get-Process | Where-Object { $_.Name -eq 'notepad' } | Stop-Process");
                
                // 执行脚本
                powerShell.Invoke();

                // 获取$lastexitcode的值
                var exitCode = powerShell.Runspace.SessionStateProxy.GetVariable("lastexitcode");

                Console.WriteLine($"The last exit code was: {exitCode}");
            }
        }
    }
}