Why is the same code not running now？

### Describe the bug
I used to be able to successfully obtain data using the following code, but now the data cannot be displayed
The hardware I am using is Canable.

### Additional context

OS and version:Windows10/Ubuntu 24.04
Python version:Python3.10/Python3.12
python-can version:4.2.0/4.4.2
python-can interface/s (if applicable):slcan

Traceback and logs

The environment that was once able to run successfully：
```python
cantools==39.3.0
mqtt==0.0.1
paho-mqtt==1.6.1
pyserial==3.5
python-can==4.2.0

```

this is my code example,It was once able to run successfully.
```python
# This is a sample Python script.
import asyncio
import time
from typing import List

import can
from can.notifier import MessageRecipient
# import cantools
import serial.tools.list_ports

# import paho.mqtt.client as mqtt
# import json

# client = mqtt.Client()
# db = cantools.database.load_file('.\wuling.dbc')

def on_connect(client, userdata, flags, rc):
print(f"Connected with result code {rc}")

async def main() -> None:
port = None
ports_list = list(serial.tools.list_ports.comports())
if len(ports_list) <= 0:
print("无串口设备,即将退出...")
time.sleep(2)
exit(0)
else:
print("可用的串口设备如下：")
for comport in ports_list:
print(comport.name + "，描述：" + str(comport.description) + "，设备ID：" + str(comport.vid) + ":" + str(
comport.pid))

for comport in ports_list:
if comport.pid == 4478 and comport.vid == 5840:
print("选择第一个CAN设备：" + comport.name + " " + str(comport.description))
port = comport
break

if port is None:
print("未发现CAN设备,即将退出...")
time.sleep(2)
exit(0)

# client.on_connect = on_connect
# client.username_pw_set(username="user", password="user")
# client.connect("127.0.0.1", 1883, 60)
"""The main function that runs in the loop."""

with can.interface.Bus(bustype='slcan', channel=str(port.name), bitrate=500000, ) as bus:
reader = can.AsyncBufferedReader()
listeners: List[MessageRecipient] = [
reader,
]
loop = asyncio.get_running_loop()
notifier = can.Notifier(bus, listeners, loop=loop)
while True:
msg = await reader.get_message()
try:
print(msg)
except Exception as ex:
print(ex)
pass
pass

if __name__ == "__main__":
asyncio.run(main())

```