e.After.VoiceChannel.Name Discord.NET - 无法找出空错误

Question

在您判断我发布另一个NullReferenceException问题之前，请阅读我的代码。我已经谷歌搜索了一段时间了nullReferenceException错误，这并不能解释为什么此特定部分给我一个错误。

    if (e.After.VoiceChannel.Name != null)

我还研究了discord.net的文档，但是，这也没有产生。这是整个文件。

using Discord;
using Discord.Commands;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
namespace DiscBot
{
    class myBot
    {
        DiscordClient discord;
        public myBot()
        {
            discord = new DiscordClient(x => 
            {
                x.LogLevel = LogSeverity.Info;
                x.LogHandler = Log;
            });
            discord.UsingCommands(x => 
            {
                x.PrefixChar = '~';
                x.AllowMentionPrefix = true;
                x.HelpMode = HelpMode.Public;
            });
            var commands = discord.GetService<CommandService>();
            commands.CreateCommand("greet")
                .Description("Does a thing")
                .Parameter("theGreeted", ParameterType.Unparsed)
                .Do(async (e)=> 
                {
                    var msgtoRead = e.Channel.DownloadMessages(1);
                    await e.Channel.SendTTSMessage("Hello " + e.GetArg("theGreeted"));
                });
            discord.UserUpdated += async (s, e) => {
                var channel = e.Server.FindChannels("general", ChannelType.Text).FirstOrDefault();
               string usrnm = e.After.Name;
                // This shouldn't get an error
                // But when I run the code I
                // get a Null Reference Exception
                if (e.After.VoiceChannel.Name != null)
                {
                    await channel.SendMessage(usrnm + " to " + e.After.VoiceChannel.Name);
                }
                else
                {
                    await channel.SendMessage(usrnm + " exited");
                }
            };

            discord.UserJoined += async (s, e) =>
            {
                var channel = e.Server.FindChannels("mainbois", ChannelType.Text).FirstOrDefault();
                var user = e.User;
                await channel.SendTTSMessage(string.Format("Another human has entered..."));
            };
            discord.ExecuteAndWait(async () =>
            {
                await discord.Connect("MYBOTTOKEN", TokenType.Bot);
            });
        }
        private void Log(object sender, LogMessageEventArgs e)
        {
        Console.WriteLine(e.Message);
        }
    }
}     

任何帮助都非常感谢。预先感谢！

P.S。如果我在某个地方犯了一个简单的错误，请仔细阅读。：p

Answer 1

发现我无法检查

if (e.After.VoiceChannel.Name != null)

如果VoiceChannel为空。换句话说，我无法基于空的值检查一个值(如果有任何意义(。我的新代码看起来像

if (e.After.VoiceChannel != null)

感谢任何花时间看我的代码的人。：D