Fix: Graceful handling of 404 errors in github_emu_group_mapping resource

[coreylane]

Resolves #2384

---

Before the change?

• The resourceGithubEMUGroupMappingRead function was not handling 404 errors correctly when an EMU external group ID was deleted outside of Terraform. This caused Terraform to fail with an error instead of gracefully removing the resource from the state.

Terraform planned the following actions, but then encountered a problem:

  # module.teams.github_team.this["testusers"] will be destroyed
  # (because key ["testusers"] is not in for_each map)
  - resource "github_team" "this" {
      - create_default_maintainer = false -> null
      - description               = "Updated: 2024-09-10T20:04:15Z" -> null
      - id                        = "12345678" -> null
      - members_count             = 5 -> null
      - name                      = "testusers" -> null
      - node_id                   = "T_XXXXXXXXXXXXX" -> null
      - privacy                   = "closed" -> null
      - slug                      = "testusers" -> null
        # (4 unchanged attributes hidden)
    }

Plan: 0 to add, 0 to change, 1 to destroy.

╷
│ Error: GET https://api.github.com/orgs/MY-EMU-ORG/external-group/123456: 404 Not Found []
│ 
│   with module.teams.github_emu_group_mapping.this["testusers"],
│   on modules/teams/main.tf line 15, in resource "github_emu_group_mapping" "this":
│   15: resource "github_emu_group_mapping" "this" {

After the change?

• The resourceGithubEMUGroupMappingRead function now properly handles 404 errors by removing the resource from Terraform's state when the EMU external group id is not found.
• Added a check for 404 status code in the API response.
• If a 404 is encountered, the resource ID is set to an empty string, effectively removing it from Terraform's state.

Terraform will perform the following actions:

  # module.teams.github_team.this["testusers"] will be destroyed
  # (because key ["testusers"] is not in for_each map)
  - resource "github_team" "this" {
      - create_default_maintainer = false -> null
      - description               = "Updated: 2024-09-12T01:04:25Z" -> null
      - id                        = "123456778" -> null
      - members_count             = 0 -> null
      - name                      = "testusers" -> null
      - node_id                   = "T_XXXXXXXXXXXX" -> null
      - privacy                   = "closed" -> null
      - slug                      = "testusers" -> null
        # (4 unchanged attributes hidden)
    }

Plan: 0 to add, 0 to change, 1 to destroy.

Changes to Outputs:
  ~ teams                                = {
      ~ github_emu_group_mapping = {
          - testusers           = {
              - group_id  = 123456
              - id        = "teams/testusers/external-groups"
              - team_slug = "testusers"
            }
            # (12 unchanged attributes hidden)
        }
      ~ github_teams             = {
          - testusers           = {
              - create_default_maintainer = false
              - description               = "Updated: 2024-09-12T01:04:25Z"
              - id                        = "12345678"
              - ldap_dn                   = ""
              - members_count             = 0
              - name                      = "testusers"
              - node_id                   = "T_XXXXXXXXXXXXXXX"
              - parent_team_id            = ""
              - parent_team_read_id       = ""
              - parent_team_read_slug     = ""
              - privacy                   = "closed"
              - slug                      = "testusers"
            }
            # (12 unchanged attributes hidden)
        }
      ~ idp_groups               = {
          - testusers           = {
              - group_id   = 123456
              - group_name = "TestUsers"
              - updated_at = "2024-09-12T01:04:25Z"
            }
            # (12 unchanged attributes hidden)
        }
    }

Pull request checklist

• Tests for the changes have been added (for bug fixes / features)
• Docs have been reviewed and added / updated if needed (for bug fixes / features)

Does this introduce a breaking change?

Please see our docs on breaking changes to help!

• Yes
• No

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[kfcampbell]

👍 thanks! I'll cut a release shortly.