when closing websocket at end of call send ws code 1000

lib/utils/ws-requestor.js

@@ -166,8 +166,9 @@ class WsRequestor extends BaseRequestor {
     this.logger.debug('WsRequestor:close closing socket');
     try {
       if (this.ws) {
-        this.ws.close();
+        this.ws.close(1000);
         this.ws.removeAllListeners();
+        this.ws = null;
       }
 
       for (const [msgid, obj] of this.messagesInFlight) {