discord.js中try catch无法捕获Embed非法URL报错问题求助

• 你当前的try/catch只能捕获同步执行代码抛出的错误，而message.channel.send()是异步方法，返回Promise对象，它内部抛出的错误属于异步错误，同步的try/catch无法捕获，因此会导致进程直接崩溃。
• 你的代码本身还存在语法错误：console.log(error) 后面直接链式调用.setTitle()是无效的，console.log返回值为undefined，调用undefined.setTitle()会额外抛出错误。

方法1：使用async/await改写逻辑，让try/catch可以捕获异步错误 #

你只需要给外层处理函数加上async关键字，给异步的send方法加上await即可，修正后的代码如下：

// 注意！要给当前这个事件处理函数加async关键字，示例：
// client.on('messageCreate', async (message) => { 这里必须加async
try {
    let json = message.content.split(" ")
    json.shift() // 移除命令前缀部分，保留JSON内容
    let data = json.join(" ")
    let embedjson = new Discord.MessageEmbed(JSON.parse(data))
    // 给send方法加await
    await message.channel.send({ embeds: [embedjson]})
} catch (error) {
    console.log(error)
    // 链式调用要接在MessageEmbed实例后面
    let errorembed = new Discord.MessageEmbed()
        .setTitle('Error!')
        .setDescription(`Something went wrong! There are a few possible issues:\n1. You tried to put text in a link option (Like putting 'hello' in the image option, or 'never gonna give you up' in the thumbnail option.)\n2. Something else\nI'll attatch the error below:`)
        .addField('Error Message', error.toString())
    await message.channel.send({ embeds: [errorembed]})
}

方法2：使用Promise的.catch()方法单独捕获send的错误 #

如果你不想改异步写法，也可以直接给send方法链式调用.catch()处理错误：

try {
    let json = message.content.split(" ")
    json.shift()
    let data = json.join(" ")
    let embedjson = new Discord.MessageEmbed(JSON.parse(data))
    message.channel.send({ embeds: [embedjson]})
        .catch(error => {
            console.log(error)
            let errorembed = new Discord.MessageEmbed()
                .setTitle('Error!')
                .setDescription(`Something went wrong! There are a few possible issues:\n1. You tried to put text in a link option (Like putting 'hello' in the image option, or 'never gonna give you up' in the thumbnail option.)\n2. Something else\nI'll attatch the error below:`)
                .addField('Error Message', error.toString())
            message.channel.send({ embeds: [errorembed]})
        })
} catch (error) {
    // 这里捕获JSON解析、Embed构造阶段的同步错误
    console.log(error)
    let errorembed = new Discord.MessageEmbed()
        .setTitle('Error!')
        .setDescription(`Something went wrong! There are a few possible issues:\n1. Invalid JSON format\n2. Incorrect Embed field structure\nI'll attatch the error below:`)
        .addField('Error Message', error.toString())
    message.channel.send({ embeds: [errorembed]})
}

你可以在构造Embed之后、发送之前提前校验图片、缩略图等字段的URL格式，提前拦截不符合要求的输入，不需要等到发送时才抛出错误：

• 校验Embed的image.url、thumbnail.url、author.iconURL、footer.iconURL等字段是否以http://或https://开头
• 校验不通过直接返回错误提示，不需要执行发送逻辑

内容的提问来源于stack exchange，提问作者johng3587