Patched code sample

import tornado.web
import tornado.websocket
import tornado.ioloop
import json
import logging

class WebSocket(tornado.websocket.WebSocketHandler):
    def open(self):
        print("WebSocket opened")

    def on_message(self, message):
        try:
            data = json.loads(message)

            if not isinstance(data, dict) or "type" not in data:
                self.close(reason="Invalid message format")
                return

        except json.JSONDecodeError:
            self.close(reason="Invalid JSON format")
        except Exception as e:
            logging.error(f"Error while processing message: {e}")
            self.close(reason="Internal server error")

    def on_close(self):
        print("WebSocket closed")

    def check_origin(self, origin):
        allowed_origins = ["http://your-allowed-origin.com"]
        if origin not in allowed_origins:
            return False
        return True

application = tornado.web.Application([
    (r'/websocket', WebSocket),
])

if __name__ == "__main__":
    application.listen(8888)
    tornado.ioloop.IOLoop.current().start()