Discord.JS fetchMessage()

Solution 1:

> If you are using Discord.js v11, the issue may come from the channel id you gave in the command.
> It appears that you try to fetch messages from an user but the method .fetchMessage() takes a message id as a parameter (See Discord.js documentation).
> You can access the fetched Message with .then(callback function)

Fix

if(message.content.startsWith(prefix + "edit"))
 {
     message.delete();
     let guild = client.guilds.get('server-id');
     const channel = args[0];
     const messageId = args[1];
     let newMessage = args.slice(2).join(' ');
     let fetchedChannel = guild.channels.get(channel);
     if (!fetchedChannel) return console.log('Channel not found');
     fetchedChannel.fetchMessage(messageId).then(message => {
         message.edit(newMessage);
     }).catch(error => console.error(error));
}