Create kubernetes env block conditionally

I have a situation where I want to create a number of env blocks for a kubernetes_deployment. The scenario is that I’m writing a re-usable module, that our apps can use, we pass in a variable, say use_email = true. Based on this var, the env block is created, or not. My idea was to use the likes of:

locals = {
email_vars = {
    "DJANGO_EMAIL_HOST" : "mail_smtp_endpoint"
    "DJANGO_EMAIL_PORT" : "mail_smtp_port"
    "DJANGO_EMAIL_USER" : "mail_smtp_user"
    "DJANGO_EMAIL_PASSWORD" : "mail_smtp_password"
    "DJANGO_EMAIL_DOMAIN" : "mail_smtp_domain"

dynamic "env" {
            for_each = (var.use_email) ? local.email_vars : []
            content {
              name = env.key
              value_from {
                secret_key_ref {
                  name = local.environment_secret_name
                  key  = env.value

However, I am getting the error:

Error: Inconsistent conditional result types
│   on .terraform/modules/app_deploy/terraform/modules/application-deploy/ line 310, in resource "kubernetes_deployment" "app_deployment":
│  310:             for_each = (var.use_email) ? local.email_vars : []
│     ├────────────────
│     │ local.email_vars is object with 5 attributes
│     │ var.use_email is a bool, known only after apply
│ The true and false result expressions must have consistent types. The given expressions are object and tuple,
│ respectively.

and I’m not sure how to progress, any advice would be welcome, thanks in advance.

I’ve figured this out and it was a stupid mistake on my part. originally the email_vars was a list of map objects, but I changed it to just a map, but failed to also change the else part of the conditional. Sorry to waste anyone’s time