Bug: Cannot read property 'set' of undefined

[JOK3R131]

Describe the error
When I try to run the bot to run on Discord, I get this error:

Cannot read property 'set' of undefined

How To Restore
Steps to recreate the behavior:

1. Write the code:

const commandFiles = readdirSync (join (__ dirname, "commands")). Filter ((file) => file.endsWith (". Js"));
for (const file of commandFiles) {
  const command = require (join (__ dirname, "commands", `$ {file}`));
  client.commands.set (command.name, command);
}

client.on ("message", async (message) => {
  if (message.author.bot) return;
  if (! message.guild) return;

  const prefixRegex = new RegExp (`^ (<@!? $ {client.user.id}> | $ {escapeRegex (PREFIX)}) \\ s *`);
  if (! prefixRegex.test (message.content)) return;

  const [, matchedPrefix] = message.content.match (prefixRegex);

  const args = message.content.slice (matchedPrefix.length) .trim (). split (/ + /);
  const commandName = args.shift (). toLowerCase ();

  const command =
    client.commands.get (commandName) ||
    client.commands.find ((cmd) => cmd.aliases && cmd.aliases.includes (commandName));

  if (! command) return;

  if (! cooldowns.has (command.name)) {
    cooldowns.set (command.name, new Collection ());
  }

  const now = Date.now ();
  const timestamps = cooldowns.get (command.name);
  const cooldownAmount = (command.cooldown || 1) * 1000;

  if (timestamps.has (message.author.id)) {
    const expirationTime = timestamps.get (message.author.id) + cooldownAmount;

    if (now <expirationTime) {
      const timeLeft = (expirationTime - now) / 1000;
      return message.reply (
        `Please wait $ {timeLeft.toFixed (1)} before using \` $ {command.name} \ `. I cannot be rushed forever! '
      );
    }
  }

  timestamps.set (message.author.id, now);
  setTimeout (() => timestamps.delete (message.author.id), cooldownAmount);

  try {
    command.execute (message, args);
  } catch (error) {
    console.error (error);
    message.reply ("This is a bad command !.");
  }
});

2. Run the bot

Expected behavior
I was expecting to turn on the bot and test the commands.

JS environment?
Node.js version: probably 12

Additional information and screenshots
none

[eritislami]

Why make bad code changes and then start an issue about it? Converting to discussion