Terraform Nested maps of different sizes - terraform

Question

I am deploying a number of AWS application load balancers by feeding a nested map from locals.tf to a module configuring the load-balancers.
locals {
lb_vars = {
alb1 = {
load_balancer_type = application
listener_port = 443
listener_protocol = https
internal = false
subnets = var.subnet1
backends = {
backend1 = {
port = "8080"
path = ["/endpoint1/backend1*"]
protocol = "http"
protocol_version = "http1"
health_check_enabled = true
health_check_interval = 10
health_check_port = 19808
health_check_path = "/health"
health_check_protocol = "http"
},
backend2 = {
port = "8081"
path = ["/endpoint1/backend2*"]
protocol = "http"
protocol_version = "http1"
health_check_enabled = true
health_check_interval = 10
health_check_port = 19809
health_check_path = "/health"
health_check_protocol = "http"
},
alb2 = {
load_balancer_type = application
listener_port = 443
listener_protocol = https
internal = false
subnets = var.subnet1
backends = {
backend1 = {
port = "8082"
path = ["/endpoint2/backend1*"]
protocol = "http"
protocol_version = "http1"
health_check_enabled = true
health_check_interval = 10
health_check_port = 19810
health_check_path = "/health"
health_check_protocol = "http"
},
backend2 = {
port = "8083"
path = ["/endpoint2/backend2*"]
protocol = "http"
protocol_version = "http1"
health_check_enabled = true
health_check_interval = 10
health_check_port = 19811
health_check_path = "/health"
health_check_protocol = "http"
},
}
}
}
}
Resource in load-balancer module:
resource "aws_lb" "lb" {
for_each = var.lb_vars
name = "${each.key}-${var.env_name}"
internal = try(each.value.internal, "false")
load_balancer_type = try(each.value.load_balancer_type, "application")
security_groups = aws_security_group.lb_security_group[each.key]
subnets = each.value.subnets
enable_deletion_protection = false
tags = "Name" = "${each.key}-${var.env_name}"
}
As one can see, there are a number of parameters which I would like to not define for each AWS lb because typically they are the defaults, but if I remove one of the parameters I get the following error;
Error: Invalid value for module argument
The given value is not suitable for child module variable "lb_vars" defined
at lb/variables.tf:41,1-21: all map elements must have the same type.
Load-balancer Module
module "lb" {
source = "./lb"
env_name = var.env_name
full_env_name = local.full_env_name
subnet_ids = local.subnet_ids
vpc_id = data.aws_vpc.vpc.id
external_zone_id = data.aws_route53_zone.external.zone_id
common_tags = local.common_tags
env_cert_arn = data.aws_acm_certificate.wildcard_cert.arn
lb_params = local.lb_params
}
Variables.tf in load-balancer modules (line 41 as per error)
variable "lb_params" {
type = map
description = "LB parameters"
}