Errors

Catch FluxerError, read ErrorCodes, and turn API failures into useful replies.

User-facing validation and not-found cases in @fluxerjs/core throw FluxerError with an ErrorCodes value. Prefer checking the code over scraping the message string.

Catch and inspect

javascript

import { FluxerError, ErrorCodes } from '@fluxerjs/core';

try {
  await guild.fetchMember(userId);
} catch (err) {
  if (err instanceof FluxerError && err.code === ErrorCodes.MemberNotFound) {
    await message.reply('That user is not in this server.');
    return;
  }
  console.error(err);
  await message.reply('Something went wrong.');
}

FluxerError often wraps a REST failure in cause. HTTP status may live on err.statusCode or err.cause?.statusCode depending on the path.

Common codes

Exact members live on ErrorCodes. Ones you will hit early:

Situation	Typical code
Channel / message / member missing	`*NotFound` family
Bad fetch limit	`INVALID_FETCH_LIMIT`
Validation on a public method	named code for that check

Builders (EmbedBuilder, etc.) may still throw plain RangeError for length limits. That is intentional.

Pattern for commands

Keep handlers boring: try the mutation, map known codes to a short reply, log everything else.

javascript

try {
  await guild.ban(userId, { reason, deleteMessageDays: 1 });
  await message.reply(`Banned <@${userId}>.`);
} catch (err) {
  if (err instanceof FluxerError && err.code === ErrorCodes.MemberNotFound) {
    await message.reply('User not found.');
    return;
  }
  throw err; // or log + generic reply
}

See moderation-bot for this pattern in a full bot.