fix Mailbox

package.json

@@ -1,6 +1,6 @@
 {
   "name": "udn",
-  "version": "1.0.0-beta11",
+  "version": "1.0.0-beta12",
   "description": "A websocket-based infrastructure for decentralized networks ",
   "bin": {
     "start": "index.ts"

subscriptionHandler.ts

@@ -101,7 +101,7 @@ export class Mailbox implements Subscriber {
 
   sendUnreadMessages(): void {
     this.messages.forEach((message) => {
-      if (!this._ws) return;
+      if (this._ws?.readyState != 1) return;
 
       this._ws.send(message);
       this.messages.delete(message);