Discord js TypeError: Cannot read property members - discord.js

Question

Hello i have this code,
user = message.guild.members.fetch(id2).then((use,err)
And i have this error
TypeError: Cannot read property 'members' of null
Please can yuo help me ?
Thank you

Answer 1

message.guild is not initialized. You could check if it is null before use eg
if(message.guild){
user = message.guild.members.fetch(id2).then((use,err) ...
}else{
//do something when it is not initialized
}

Answer 2

Your error occurs because the message object refers to a message that was received as a DM. Because of how DMs work, there is no guild or member property for such message (they are left as nulls).
To avoid that, you should handle direct messages slightly differently. The easiest and most commonly used way is to completely stop direct messages from running your message event code. This can be done by adding
if (message.channel.type === 'dm') return;
at the very top of your event.
As that makes it impossible to initiate commands in DMs, even if they don't need to be executed in a guild to work (like ping command for example), this might be not what you want. In such case, you should implement a way to determine if command someone tried to run in DM is "allowed" to be executed there. Implementations for that vary depending on command handling implementation, but snippet below is basic princinple.
client.on('message', message => {
if (message.author.bot || !message.startsWith(prefix)) return;
const args = message.content.slice(prefix.length).split(/ /g);
const command = args.shift().toLowerCase();
if (command === 'memberinfo') {
if (message.channel.type === 'dm') return message.reply('this command cannot be run in DMs.');
// Actual command code
}
});