重新验证服务器内容长度不匹配

Question

我在节点中设置了自己的Restify服务器来提供HTML：

const ServeHTML = (folder: string, page: string, res: Restify.Response, data: Object) => {
    let path:string = __dirname+"/../../"+folder+page;
    let MimeType: string | null = Mime.getType(path);
    if(!MimeType) MimeType = "";
    let body:string = fs.readFileSync(path, "utf8");
    res.writeHead(200, {
        'Content-Length': Buffer.byteLength(body, "utf8"),
        'Content-Type': MimeType
    });

    Object.keys(data).forEach(function(key,index) {
        let regex = new RegExp("{{"+key+"}}", 'gi');
        body = body.replace(regex, (<any>data)[key]);
    });
    res.write(body);
    res.end();
}

如您所见，我已经在计算Content-Length。但是，我仍然收到错误：

GET http://localhost:4000/WebChat net::ERR_CONTENT_LENGTH_MISMATCH 200 (OK)

我在做什么错了？