fix: prevent 'undefined' debug message on intentional shard closure (#…

…9846)

* style: prevent 'undefined' debug message on intentional shard closure

addresses #9594

* refactor(WebSocketManager#destroy): improve debug messaging

cleaner stacktrace format
gracefully closing shards will display an appropriate debug `reason`

* style: unresumable debug messaging

---------

Co-authored-by: Almeida <almeidx@pm.me>

packages/discord.js/src/client/websocket/WebSocketManager.js

@@ -258,7 +258,7 @@ class WebSocketManager extends EventEmitter {
          * @param {number} id The shard id that disconnected
          */
         this.client.emit(Events.ShardDisconnect, { code, reason: reasonIsDeprecated, wasClean: true }, shardId);
-        this.debug(GatewayCloseCodes[code], shardId);
+        this.debug(`Shard not resumable: ${code} (${GatewayCloseCodes[code] ?? CloseCodes[code]})`, shardId);
         return;
       }
 
@@ -324,9 +324,9 @@ class WebSocketManager extends EventEmitter {
   async destroy() {
     if (this.destroyed) return;
     // TODO: Make a util for getting a stack
-    this.debug(`Manager was destroyed. Called by:\n${new Error().stack}`);
+    this.debug(Object.assign(new Error(), { name: 'Manager was destroyed:' }).stack);
     this.destroyed = true;
-    await this._ws?.destroy({ code: CloseCodes.Normal });
+    await this._ws?.destroy({ code: CloseCodes.Normal, reason: 'Manager was destroyed' });
   }
 
   /**