feat(Interactions): improve error handling for ephemeral responses (#5892)

Co-authored-by: muchnameless <12682826+muchnameless@users.noreply.github.com>

src/structures/CommandInteraction.js

@@ -58,6 +58,12 @@ class CommandInteraction extends Interaction {
      */
     this.replied = false;
 
+    /**
+     * Whether the reply to this interaction is ephemeral
+     * @type {?boolean}
+     */
+    this.ephemeral = null;
+
     /**
      * An associated interaction webhook, can be used to further interact with this interaction
      * @type {InteractionWebhook}