尝试从文件加载令牌时发生Discord.py事件循环关闭错误

import discord
import asyncio

async def load_token(file_path):
    try:
        with open(file_path, 'r') as file:
            token = file.read().strip()
        return token
    except FileNotFoundError:
        print(f"Token file not found: {file_path}")
        return None

async def main():
    token = await load_token('token.txt')
    if token:
        client = discord.Client()
        @client.event
        async def on_ready():
            print(f'Logged in as {client.user}')
        
        await client.start(token)
    else:
        print("Failed to load token.")

# 确保在事件循环中运行主函数
if __name__ == "__main__":
    loop = asyncio.get_event_loop()
    try:
        loop.run_until_complete(main())
    finally:
        loop.close()