fix: remove repository file from state when its commit no longer exists

[erikmiller-gusto]

Resolves #3586

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Before the change?

• resourceGithubRepositoryFileRead returns a hard error when the file's commit can no longer be found. Both lookup paths fall through to a bare return diag.FromErr(err): a GitHub 404 from GetCommit (used when commit_sha is in state), and getFileCommit's cannot find file ... case (used when it is not).
• Because read fails rather than clearing the ID, once the commit is unreachable the resource can neither be refreshed nor removed — every later plan/apply fails on the same read, and the entry needs manual state surgery to clear.
• This is inconsistent with the sibling repository resources: resource_github_repository_custom_property.go, resource_github_repository_ruleset.go and resource_github_branch_default.go already detect a 404 on read and call d.SetId("").

After the change?

• A read that establishes the commit is gone removes the resource from state, matching Terraform's contract and the sibling resources.
• getFileCommit's exhaustion case is wrapped in an errFileCommitNotFound sentinel so the read can tell it apart from a genuine failure without string matching. That case is reachable independently of any HTTP status, which is why a sentinel is used rather than only checking for a 404.
• Every error that is not "not found" still propagates unchanged.

Pull request checklist

• Schema migrations have been created if needed — no schema change; this only affects read behaviour.
• Tests for the changes have been added (for bug fixes / features)
• Docs have been reviewed and added / updated if needed — no user-facing schema or option change, so I did not find anything in website/ that describes this behaviour. Happy to document it if you would like it called out.

Does this introduce a breaking change?

• Yes
• No

A configuration whose file still exists is unaffected. The change only alters what happens when the commit is already gone, where the previous outcome was a permanent read error.

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Testing

Test_getFileCommit_NoCommitContainsFile drives getFileCommit against an httptest server that returns an empty commit list, and asserts errors.Is(err, errFileCommitNotFound). It uses the existing mustCreateTestGitHubClient helper and needs no credentials. I verified it discriminates: removing the %w wrap makes it fail with errors.Is(...) = false, which is the regression that would silently restore the old behaviour.

I could not exercise the resource-level 404 path, since the acceptance tests need a live org and credentials I do not have. Note that go test ./github/... does not pass cleanly on a fresh checkout in my environment either — TestAccGithubActionsOrganizationPermissions panics without credentials — and I confirmed that failure is identical with and without this change. go build ./..., go vet ./github/... and gofmt -l are clean.

AI use

Per the AI Use Policy: this change was written with AI assistance. I have reviewed it, and the verification described above is what I actually ran rather than a summary of intent. The reasoning for the sentinel over a status-code-only check, and the scope limits above, are stated deliberately — please push back if you would rather solve it differently, for example by handling the exhaustion case at the call site instead.

🤖

[github-actions]

👋 Hi, and thank you for this contribution!

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[deiga]

Please use t.Context() instead

[Copilot]

Pull request overview

These provider review instructions are being used.

The PR aims to handle unreachable repository-file commits during Terraform refresh. However, it can remove an existing file from state and lacks resource-level regression coverage.

Changes:

• Adds an errFileCommitNotFound sentinel.
• Clears state for missing commits.
• Adds sentinel-wrapping coverage.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 2 comments.

File	Description
github/util_repo.go	Adds and wraps the commit-not-found sentinel.
github/util_repo_test.go	Tests sentinel detection.
github/resource_github_repository_file.go	Handles commit lookup failures during read.

Suppressed comments (1)

github/resource_github_repository_file.go:346

• This sentinel also does not establish that the managed file is gone: getFileCommit is called only after GetContents returned the current file successfully. Removing the ID here therefore schedules creation of a file that still exists and normally fails unless overwrite_on_create is enabled. Preserve the resource in state and propagate/handle the commit-metadata lookup failure instead; absence is already handled by the earlier contents lookup.

		if errors.Is(err, errFileCommitNotFound) {
			tflog.Info(ctx, "Removing repository file from state because no commit contains it")
			d.SetId("")
			return nil