Contagem de índice do Terraform

Sou novo no Terraform e estou praticando a criação do meu primeiro terraform. Encontrei um erro do qual não tenho certeza e, ao revisar os mesmos erros on-line, não está claro o que devo fazer. Parece que há uma questão fundamental de “tipo” aqui. Alguém pode destacar o que precisa ser feito e por quê.

Erro:

 terraform validate
╷
│ Error: Missing resource instance key
│
│   on variables.tf line 32, in output "public_ip":
│   32:   value       = aws_instance.my_rhel9_vm.public_ip
│
│ Because aws_instance.my_rhel9_vm has "count" set, its attributes must be accessed on specific instances.
│
│ For example, to correlate with indices of a referring resource, use:
│     aws_instance.my_rhel9_vm[count.index]
╵
╷
│ Error: Missing resource instance key
│
│   on variables.tf line 37, in output "instance_id":
│   37:   value       = aws_instance.my_rhel9_vm.id
│
│ Because aws_instance.my_rhel9_vm has "count" set, its attributes must be accessed on specific instances.
│
│ For example, to correlate with indices of a referring resource, use:
│     aws_instance.my_rhel9_vm[count.index]
╵

main.tf

provider "aws" {
  access_key = var.aws_access_key_id
  secret_key = var.aws_secret_access_key
  region     = "us-east-1"
}

resource "aws_instance" "my_rhel9_vm" {
  ami           = var.ami //RHEL 9 AMI
  instance_type = var.type
  count         = var.number_of_instances
  key_name      = var.ami_key_pair_name

  tags = {
    Name = "${var.name_tag}"
  }
}

variables.tf

variable "ami" {
  type        = string
  description = "RHEL 9 AMI ID in US-East-1"
  default     = "ami-05a5f6298acdb05b6"
}

variable "type" {
  type        = string
  description = "Instance Type"
  default     = "t2.micro"
}

variable "name_tag" {
  type        = string
  description = "Name of the EC2 instance"
  default     = "My EC2 RHEL 9 instance"
}

variable "number_of_instances" {
  type        = number
  description = "Number of instances to be created"
  default     = 1
}

variable "ami_key_pair_name" {
  type        = string
  description = "SSH Key Pair"
  default     = "tomcat"
}

output "public_ip" {
  value       = aws_instance.my_rhel9_vm.public_ip
  description = "Public IP Address of EC2 instance"
}

output "instance_id" {
  value       = aws_instance.my_rhel9_vm.id
  description = "Instance ID"
}

variable "aws_access_key_id" {}
variable "aws_secret_access_key" {}

#locals {
# ami      = "ami-05a5f6298acdb05b6"
# type     = "t2.micro"
# name_tag = "My EC2 RHEL 9 instance"
#}