invalid count argument on read/write_target_index with multiple dynamodb tables

[leevs]

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Describe the Bug

Error: Invalid count argument for read_target_index & write_target_index with running plan or apply.

  on .terraform/modules/dynamodb_table_randomname.dynamodb_autoscaler/main.tf line 92, in resource "aws_appautoscaling_target" "read_target_index":
  92:   count              = var.enabled ? length(var.dynamodb_indexes) : 0

Code is:

resource "aws_kms_key" "kms_random" {
  description                 = "KMS key for inbox project"
} 

module "dynamodb_table_random1" {
  source                              = "git::https://github.com/cloudposse/terraform-aws-dynamodb.git?ref=tags/0.22.0"
  server_side_encryption_kms_key_arn  = aws_kms_key.kms_random.arn
  namespace                           = var.company
  stage                                     = var.aws_env
  name                                     = "random1"
  hash_key                               = "random1"
  autoscale_write_target              = 50
  autoscale_read_target               = 50
  autoscale_min_read_capacity         = 10
  autoscale_max_read_capacity         = 200
  autoscale_min_write_capacity        = 10
  autoscale_max_write_capacity        = 200
  enable_autoscaler                   = true

  dynamodb_attributes = [
    {
      name = "random1"
      type = "S"
    }
  ]
}

module "dynamodb_table_random2" {
  source                              = "git::https://github.com/cloudposse/terraform-aws-dynamodb.git?ref=tags/0.22.0"
  server_side_encryption_kms_key_arn  = aws_kms_key.kms_random.arn
  namespace                           = var.company
  stage                                     = var.aws_env
  name                                     = "random2"
  hash_key                               = "random2"
  autoscale_write_target              = 50
  autoscale_read_target               = 50
  autoscale_min_read_capacity         = 10
  autoscale_max_read_capacity         = 200
  autoscale_min_write_capacity        = 10
  autoscale_max_write_capacity        = 200
  enable_autoscaler                   = true

  dynamodb_attributes = [
    {
      name = "random2"
      type = "S"
    }
  ]
}

Expected Behavior

It should be able to run a plan and apply with local state without specifying a -out at the plan phase and apply with the output.
OR
by doing staged plan & apply with -target

Steps to Reproduce

Steps to reproduce the behavior:

1. terraform plan (will work)
2. terraform apply (will fail because of the count)

Works for me once

1. terraform plan -out plan
2. terraform apply "plan"
3. terraform plan (does not work anymore)

Or it also works with -target but this is not the way we would want to work.

Environment (please complete the following information):

Terraform v0.13.5

• provider registry.terraform.io/hashicorp/aws v3.16.0
• provider registry.terraform.io/hashicorp/null v2.1.2

Additional Context

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