Repository: discordjs/discord.js
File: packages/discord.js/src/structures/Message.js (JavaScript)

Code before:
   *   .catch(console.error);
   */
  reply(options) {
    let data;

    if (options instanceof MessagePayload) {
      data = options;
    } else {
      data = MessagePayload.create(this, options, {
        messageReference: {
          messageId: this.id,
          channelId: this.channelId,
          guildId: this.guildId,
          type: MessageReferenceType.Default,
          failIfNotExists: options?.failIfNotExists ?? this.client.options.failIfNotExists,
        },
      });
    }
    return this.client.channels.createMessage(this.channelId, data);
  }

  /**
   * Forwards this message.
   * @param {TextChannelResolvable} channel The channel to forward this message to.
   * @returns {Promise<Message>}
   */
  forward(channel) {
    return this.client.channels.createMessage(channel, {
      messageReference: {
        messageId: this.id,
        channelId: this.channelId,
        guildId: this.guildId,
        type: MessageReferenceType.Forward,
      },
    });
  }

  /**
   * Options for starting a thread on a message.
   * @typedef {Object} StartThreadOptions
   * @property {string} name The name of the new thread
   * @property {ThreadAutoArchiveDuration} [autoArchiveDuration=this.channel.defaultAutoArchiveDuration] The amount of
   * time after which the thread should automatically archive in case of no recent activity
   * @property {string} [reason] Reason for creating the thread
   * @property {number} [rateLimitPerUser] The rate limit per user (slowmode) for the thread in seconds
   */

  /**
   * Create a new public thread from this message
   * @see GuildTextThreadManager#create
   * @param {StartThreadOptions} [options] Options for starting a thread on this message

Review comment (bug):
Target must (currently?) be something with a `client`, which a `string` isn't.
e.g. `this.target.client.options.failIfNotExists` would throw an error.

Code after:
   * Send an inline reply to this message.
   * @param {string|MessagePayload|MessageReplyOptions} options The options to provide
   * @returns {Promise<Message>}
   * @example
   * // Reply to a message
   * message.reply('This is a reply!')
   *   .then(() => console.log(`Replied to message "${message.content}"`))
   *   .catch(console.error);
   */
  reply(options) {
    let data;

    if (options instanceof MessagePayload) {
      data = options;
    } else {
      data = MessagePayload.create(this, options, {
        messageReference: {
          messageId: this.id,
          channelId: this.channelId,
          guildId: this.guildId ?? undefined,
          type: MessageReferenceType.Default,
          failIfNotExists: options?.failIfNotExists ?? this.client.options.failIfNotExists,
        },
      });
    }
    return this.client.channels.createMessage(this.channelId, data);
  }

  /**
   * Forwards this message.
   * @param {TextChannelResolvable} channel The channel to forward this message to.
   * @returns {Promise<Message>}
   */
  forward(channel) {
    return this.client.channels.createMessage(channel, {
      messageReference: {
        messageId: this.id,
        channelId: this.channelId,
        guildId: this.guildId ?? undefined,
        type: MessageReferenceType.Forward,
      },
    });
  }

  /**
   * Options for starting a thread on a message.
   * @typedef {Object} StartThreadOptions
   * @property {string} name The name of the new thread
   * @property {ThreadAutoArchiveDuration} [autoArchiveDuration=this.channel.defaultAutoArchiveDuration] The amount of
   * time after which the thread should automatically archive in case of no recent activity
   * @property {string} [reason] Reason for creating the thread