I am having an issue with Discord.js - discord.js

Question

I am new to discord.js and I am wondering how to fix this error. Could you please fix my code and then also tell me how to avoid this issue in the future? Thanks!
Code:
client.on('message', message => {
if (message.content === '-ping') {
const embed = {
"title": "**Ping Results**",
"fields": [
{
"name": "Bot",
"value": "" +(botMsg.createdAt - message.createdAt) + "ms"
},
{
"name": "API ",
"value": Math.round(client.ping) + "ms"
},
{
"name": "Uptime",
"value": msToTime(client.uptime) + "ms"
}
]
};
message.channel.send({ embed });
}
});
Console Error:
ReferenceError: botMsg is not defined
at Client.<anonymous> (C:\Users\parke\Documents\Discord Bot\index.js:15:31)
at Client.emit (events.js:314:20)
at MessageCreateAction.handle (C:\Users\parke\Documents\Discord Bot\node_modules\discord.js\src\client\actions\MessageCreate.js:31:14)
at Object.module.exports [as MESSAGE_CREATE] (C:\Users\parke\Documents\Discord Bot\node_modules\discord.js\src\client\websocket\handlers\MESSAGE_CREATE.js:4:32)
at WebSocketManager.handlePacket (C:\Users\parke\Documents\Discord Bot\node_modules\discord.js\src\client\websocket\WebSocketManager.js:384:31)
at WebSocketShard.onPacket (C:\Users\parke\Documents\Discord Bot\node_modules\discord.js\src\client\websocket\WebSocketShard.js:444:22)
at WebSocketShard.onMessage (C:\Users\parke\Documents\Discord Bot\node_modules\discord.js\src\client\websocket\WebSocketShard.js:301:10)
at WebSocket.onMessage (C:\Users\parke\Documents\Discord Bot\node_modules\ws\lib\event-target.js:125:16)
at WebSocket.emit (events.js:314:20)
at Receiver.receiverOnMessage (C:\Users\parke\Documents\Discord Bot\node_modules\ws\lib\websocket.js:797:20)

Answer 1

This error means that the variable botMsg is not defined.
As I can see you want to make a ping command and botMsg is a message sent that you want to collect.
This code should work.
client.on('message', message => {
if (message.content === '-ping') {
message.channel.send("Checking the ping...").then(botMsg => {
const embed = {
"title": "**Ping Results**",
"fields": [
{
"name": "Bot",
"value": "" +(botMsg.createdAt - message.createdAt) + "ms"
},
{
"name": "API ",
"value": Math.round(client.ping) + "ms"
},
{
"name": "Uptime",
"value": msToTime(client.uptime) + "ms"
}
]
};
botMsg.edit({ embed });
})
}
});