PyMongo -创建多个索引会抛出错误消息

from pymongo import MongoClient

# 连接到MongoDB数据库
client = MongoClient('mongodb://localhost:27017/')
db = client['mydatabase']
collection = db['mycollection']

# 定义要创建的索引列表
indexes = [
    [('field1', 1)],
    [('field2', -1)],
    [('field3', 1), ('field4', -1)]
]

# 遍历索引列表，检查索引是否已经存在，如果不存在则创建索引
for index in indexes:
    index_name = '_'.join([f'{field}_{order}' for field, order in index])
    if index_name not in [idx['name'] for idx in collection.list_indexes()]:
        try:
            collection.create_index(index)
            print(f"索引 {index_name} 创建成功")
        except Exception as e:
            print(f"创建索引 {index_name} 失败：{str(e)}")
    else:
        print(f"索引 {index_name} 已经存在")