forgejo_repository update fails with HTTP 500 when has_wiki=false and provider sends wiki_branch="" (Version >1.4.2)

[misl-smlz]

Bug description

When running terraform apply with terraform-provider-forgejo v1.5.0, repository update fails with:

• Error: Unable to update repository
• Unknown error (status 500):

From TRACE logs, provider sends wiki_branch="" while has_wiki=false in Update repository, and Forgejo responds with HTTP 500.

This appears after upgrading Terraform to versions later than 1.4.2 (currently reproduced on 1.14.9).

Versions

• Terraform: 1.14.9 (fails)
• terraform-provider-forgejo: v1.5.0
• Forgejo: 15.0.3
• OS: Linux

(Older Terraform 1.4.2 did not show this behavior in our setup.)

Reproduction

Minimal resource shape

resource "forgejo_repository" "this" {
  owner          = "it-devops"
  name           = "webshop"
  default_branch = "main"

  has_wiki       = false
  archived       = true
  has_issues     = true
  has_actions    = true
  has_projects   = false

  external_tracker = {
    external_tracker_url    = "https://jira.schmalz.com"
    external_tracker_format = "https://jira.schmalz.com/browse/{index}"
    external_tracker_style  = "alphanumeric"
  }
}
Command
TF_LOG=TRACE TF_LOG_PROVIDER=TRACE TF_LOG_PATH=forgejo-webshop.log \
terraform apply -var-file=terraform.tfvars -target='forgejo_repository.this["webshop"]'
Actual behavior
Apply fails with:
Error: Unable to update repository
Unknown error (status 500):
TRACE snippet (same request context):
[INFO] Update repository: ... has_wiki=false ... wiki_branch="" ... status="500 Internal Server Error"
[ERROR] Response contains error diagnostic: "Unknown error (status 500): "
Expected behavior
- Provider should not fail with 500 during update.
- If has_wiki=false, provider should avoid sending invalid/empty wiki-specific values (wiki_branch="") or otherwise normalize request payload so Forgejo accepts it.
- Ideally this should be a no-op update when no meaningful config changes are required.
Additional notes
In plan output, many optional fields are newly appearing and forcing in-place update, including:
- wiki_branch = ""
- default_update_style = "merge"
- allow_rebase_update = true
- allow_fast_forward_only_merge = false
- default_allow_maintainer_edit = false
- default_delete_branch_after_merge = false
The consistent failing signal in logs is has_wiki=false + wiki_branch="" followed by HTTP 500.