Mineflayer.js机器人调用bot.chat()崩溃，报undefined的length属性错误

问题描述 #

基于Mineflayer（依赖minecraft-protocol）开发1.19.2版本的MC机器人，调用bot.chat()时无论是否使用await都会触发序列化错误，错误核心提示为：TypeError: Serialization error for play.toServer : SizeOf error for undefined : Cannot read properties of undefined (reading 'length')。

代码示例 #

mineflayer = require('mineflayer');
let requirements = {
    'host':'mc.ip.net',
    'port':'88888',
    'version':'1.19.2'
};

class MCBot{
    // Constructor
    constructor(username){
        this.username = username;
        this.host = requirements['host'];
        this.port = requirements['port'];
        this.version = requirements['version'];

        this.initBot()
    };
    // Init Bot Instance
    initBot(){
        this.bot = mineflayer.createBot({
            'username': this.username,
            'host': this.host,
            'port': this.port,
            'version': this.version
        });
        this.initEvents()
    }
    // Init Bot Events
    initEvents(){
        // Login Event
        this.bot.on('login', ()=>{
            let botSocket = this.bot._client.socket;
            console.log(`[${this.username}] Logged in to ${botSocket.server ? botSocket.server : botSocket.host}`);
        });
        // Disconnect Event
        this.bot.on('end', ()=>{
            console.log(`[${this.username}] Disconnected`);
            // Reconnection Attempt
            setTimeout(()=> this.initBot, 2000);
        });
        // Error Event
        this.bot.on('error', (err)=>{
            if(err.code==='ECONNREFUSED'){
                console.log(`[${this.username}] Failed to Reconnect to ${err.address}:${err.port}`);
            }else{
                console.log(`[${this.username}] Unhandled Error: ${err}`);
            }
        });
        // Spawn Event
        this.bot.on('spawn', async ()=>{
            console.log(`[${this.username}]  Spawned in`);
            await this.bot.waitForTicks(0)
            this.bot.chat(`${this.username}'s Ready!`);
            /*
            await this.bot.waitForTicks(60);
            this.bot.chat("Goodbye!");
            this.bot.quit();
            */
        });
    }
}
new MCBot("Bob")
// let bots = ["Bob"]
// for(var i = 0; i<bots.length; i++){
//     bots.push(new MCBot(bots[i]))
//     console.log("Bot added")
// }

错误日志 #

[Bob] Logged in to undefined
[Bob]  Spawned in
TypeError: Serialization error for play.toServer : SizeOf error for undefined : Cannot read properties of undefined (reading 'length')
    at Object.previousMessages (eval at compile (C:\Users\xianc\Desktop\CHRIS\Minecraft\Bots\node_modules\protodef\src\compiler.js:258:12), <anonymous>:175:37)
    at Object.packet_chat_message (eval at compile (C:\Users\xianc\Desktop\CHRIS\Minecraft\Bots\node_modules\protodef\src\compiler.js:258:12), <anonymous>:599:37)
    at eval (eval at compile (C:\Users\xianc\Desktop\CHRIS\Minecraft\Bots\node_modules\protodef\src\compiler.js:258:12), <anonymous>:1222:64)
    at packet (eval at compile (C:\Users\xianc\Desktop\CHRIS\Minecraft\Bots\node_modules\protodef\src\compiler.js:258:12), <anonymous>:1270:9)
    at CompiledProtodef.sizeOf (C:\Users\xianc\Desktop\CHRIS\Minecraft\Bots\node_modules\protodef\src\compiler.js:89:14)
    at e.message (C:\Users\xianc\Desktop\CHRIS\Minecraft\Bots\node_modules\protodef\src\compiler.js:96:40)
    at tryCatch (C:\Users\xianc\Desktop\CHRIS\Minecraft\Bots\node_modules\protodef\src\utils.js:50:16)
    at CompiledProtodef.createPacketBuffer (C:\Users\xianc\Desktop\CHRIS\Minecraft\Bots\node_modules\protodef\src\compiler.js:96:20)
    at Serializer.createPacketBuffer (C:\Users\xianc\Desktop\CHRIS\Minecraft\Bots\node_modules\protodef\src\serializer.js:12:23)
    at Serializer._transform (C:\Users\xianc\Desktop\CHRIS\Minecraft\Bots\node_modules\protodef\src\serializer.js:18:18) {
  field: 'play.toServer'
}
[Bob] Unhandled Error: TypeError: Serialization error for play.toServer : SizeOf error for undefined : Cannot read properties of undefined (reading 'length')
[Bob] Disconnected

解决方案 #

1. 修正端口数据类型 #

requirements中的port被定义为字符串类型，但Mineflayer的createBot方法要求port必须是数字类型。字符串端口会导致客户端底层初始化异常，进而引发聊天数据包序列化失败。

修改代码：

let requirements = {
    'host':'mc.ip.net',
    'port':88888, // 去掉引号，改为数字类型
    'version':'1.19.2'
};

2. 修复重连逻辑错误 #

在end事件的重连代码中，setTimeout(()=> this.initBot, 2000)仅传递了函数引用，并未实际调用初始化方法，导致断开后无法重新连接。需要改为：

setTimeout(()=> this.initBot(), 2000); // 加上()调用函数

3. 确保bot实例状态稳定 #

虽然spawn事件触发代表机器人已进入世界，但可以增加状态检查并延长等待时间，确保客户端完全初始化后再执行聊天操作：

this.bot.on('spawn', async ()=>{
    console.log(`[${this.username}]  Spawned in`);
    await this.bot.waitForTicks(20); // 等待更多ticks确保客户端稳定
    if (this.bot._client && this.bot._client.state === 'play') {
        this.bot.chat(`${this.username}'s Ready!`);
    }
});

修改后的完整代码 #

mineflayer = require('mineflayer');
let requirements = {
    'host':'mc.ip.net',
    'port':88888, // 改为数字类型
    'version':'1.19.2'
};

class MCBot{
    constructor(username){
        this.username = username;
        this.host = requirements['host'];
        this.port = requirements['port'];
        this.version = requirements['version'];

        this.initBot()
    };

    initBot(){
        this.bot = mineflayer.createBot({
            'username': this.username,
            'host': this.host,
            'port': this.port,
            'version': this.version
        });
        this.initEvents()
    }

    initEvents(){
        this.bot.on('login', ()=>{
            let botSocket = this.bot._client.socket;
            console.log(`[${this.username}] Logged in to ${botSocket.remoteAddress || botSocket.host}`);
        });

        this.bot.on('end', ()=>{
            console.log(`[${this.username}] Disconnected`);
            setTimeout(()=> this.initBot(), 2000); // 修复重连调用
        });

        this.bot.on('error', (err)=>{
            if(err.code==='ECONNREFUSED'){
                console.log(`[${this.username}] Failed to Reconnect to ${err.address}:${err.port}`);
            }else{
                console.log(`[${this.username}] Unhandled Error: ${err}`);
            }
        });

        this.bot.on('spawn', async ()=>{
            console.log(`[${this.username}]  Spawned in`);
            await this.bot.waitForTicks(20);
            if (this.bot._client && this.bot._client.state === 'play') {
                this.bot.chat(`${this.username}'s Ready!`);
            }
        });
    }
}
new MCBot("Bob")

内容的提问来源于stack exchange，提问作者Christian Cangelli