feat(Message): replace referencedMessage with fetchReference (#5577)

src/errors/Messages.js

@@ -96,6 +96,7 @@ const Messages = {
   INVALID_ELEMENT: (type, name, elem) => `Supplied ${type} ${name} includes an invalid element: ${elem}`,
 
   WEBHOOK_MESSAGE: 'The message was not sent by a webhook.',
+  MESSAGE_REFERENCE_MISSING: 'The message does not reference another message',
 
   EMOJI_TYPE: 'Emoji must be a string or GuildEmoji/ReactionEmoji',
   EMOJI_MANAGED: 'Emoji is managed and has no Author.',

src/structures/Message.js

@@ -442,15 +442,16 @@ class Message extends Base {
   }
 
   /**
-   * The Message this crosspost/reply/pin-add references, if cached
-   * @type {?Message}
-   * @readonly
+   * Fetches the Message this crosspost/reply/pin-add references, if available to the client
+   * @returns {Promise<Message>}
    */
-  get referencedMessage() {
-    if (!this.reference) return null;
-    const referenceChannel = this.client.channels.resolve(this.reference.channelID);
-    if (!referenceChannel) return null;
-    return referenceChannel.messages.resolve(this.reference.messageID);
+  async fetchReference() {
+    if (!this.reference) throw new Error('MESSAGE_REFERENCE_MISSING');
+    const { channelID, messageID } = this.reference;
+    const channel = this.client.channels.resolve(channelID);
+    if (!channel) throw new Error('GUILD_CHANNEL_RESOLVE');
+    const message = await channel.messages.fetch(messageID);
+    return message;
   }
 
   /**