fix(WebSocketShard): key name in WebSocketShard#_send. (#5304)

I just changed an incorrect key name that was introduced in Pull Request #3722. When destroying the websocket from the WebSocketShard#_send method it's using `close` as the key name instead of `closeCode`

src/client/websocket/WebSocketShard.js

@@ -648,7 +648,7 @@ class WebSocketShard extends EventEmitter {
   _send(data) {
     if (!this.connection || this.connection.readyState !== WebSocket.OPEN) {
       this.debug(`Tried to send packet '${JSON.stringify(data)}' but no WebSocket is available!`);
-      this.destroy({ close: 4000 });
+      this.destroy({ closeCode: 4000 });
       return;
     }