我在 tf 计划中收到此错误：
Error: Invalid value for module argument
on ec2_asg.tf line 13, in module "ec2_asg":
13: subnets = [module.vpc.private_subnets]
The given value is not suitable for child module variable "subnets" defined at
.terraform/modules/ec2_asg/variables.tf:388,1-19: element 0: string required.
这是模块中的变量：
variable "subnets" {
description = "List of subnets for Application. e.g. ['subnet-8da92df7', 'subnet-9e5dc5f6', 'subnet-497eaf33']"
type = list(string)
}
这是在 .tf 文件中：
......
......
scaling_max = var.scaling_max_bi
subnets = [module.vpc.private_subnets]
security_groups = [aws_security_group.id]
有人可以帮我解决这个问题吗？