Terraform vague error message on length=-1 for random_string resource

[ghost]

This issue was originally opened by @bogdanbarna as hashicorp/terraform#26849. It was migrated here as a result of the provider split. The original body of the issue is below.

---

Terraform Version

Terraform v0.13.5
+ provider registry.terraform.io/hashicorp/random v3.0.0

Terraform Configuration Files

variable "name_prefix" {}

resource "random_string" "name_suffix" {
  length  = 30 - length(var.name_prefix)
  upper   = false
  special = false
}

resource "aws_instance" "web" {
  ami           = "ami-07dd19a7900a1f049"
  instance_type = "t3.micro"

  tags = {
    Name = "foo-${random_string.name_suffix.result}"
  }
}

Debug Output

Crash Output

https://gist.github.com/bogdanbarna/4181ddf0b5fe0082e6cdcf4aae8cf0e0

Expected Behavior

A specific error message appearing during plan and/or apply.

Actual Behavior

Receiving Error: rpc error: code = Unavailable desc = transport is closing on apply.

Steps to Reproduce

terraform init
terraform apply -var name_prefix=small # this works
terraform apply -var name_prefix=laaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaarge # this crashes

Additional Context

The crash report isn't created when the random_string output is used for the aws_instance input.
So apply -target=random_string creates the crash report, but apply without target does not.

References

[pyToshka]

in this case length = -12

  # random_string.name_suffix will be created
  + resource "random_string" "name_suffix" {
      + id          = (known after apply)
      + length      = -12
      + lower       = true
      + min_lower   = 0
      + min_numeric = 0
      + min_special = 0
      + min_upper   = 0
      + number      = true
      + result      = (known after apply)
      + special     = false
      + upper       = false
    }

seems like need to add checking for negative length in string.go

[github-actions]

I'm going to lock this issue because it has been closed for 30 days ⏳. This helps our maintainers find and focus on the active issues.
If you have found a problem that seems similar to this, please open a new issue and complete the issue template so we can capture all the details necessary to investigate further.