fix: address sonnet review MINOR findings (#2916)

- client.go: fix misleading timer.Stop() comment (finding #1)
- pr.go: document all-or-nothing semantics for GetCommitStatuses
  when check-runs endpoint fails after statuses succeed (finding #2)
- files.go: include both array and object unmarshal errors in
  ListContents fallback error message (finding #3)
- pr.go: expand mapCheckRunStatus comment to explain non-blocking
  policy decision (finding #4)

github/client.go

@@ -225,7 +225,7 @@ func (c *Client) doRequest(ctx context.Context, method, reqURL string, accept st
 				timer := time.NewTimer(delay)
 				select {
 				case <-timer.C:
-					timer.Stop() // no-op after fire, releases runtime resources promptly
+					timer.Stop() // no-op after fire; kept for symmetry with the ctx.Done case
 				case <-ctx.Done():
 					timer.Stop()
 					return nil, ctx.Err()

github/files.go

@@ -81,7 +81,7 @@ func (c *Client) ListContents(ctx context.Context, owner, repo, path string) ([]
 	if err := json.Unmarshal(body, &entries); err != nil {
 		var single entry
 		if err2 := json.Unmarshal(body, &single); err2 != nil {
-			return nil, fmt.Errorf("parse contents JSON: %w", err2)
+			return nil, fmt.Errorf("parse contents JSON: as array: %v; as object: %w", err, err2)
 		}
 		// Guard against empty objects ({}) or unexpected shapes that
 		// unmarshal successfully but carry no useful data.

github/pr.go

@@ -127,6 +127,9 @@ func (c *Client) GetPullRequestFiles(ctx context.Context, owner, repo string, nu
 // Returns nil (not an empty slice) when there are no statuses or check runs.
 // If the commit statuses endpoint fails (e.g. 404 for an unknown SHA), the
 // function returns immediately without attempting the check-runs endpoint.
+// If the check-runs endpoint fails after statuses were fetched successfully,
+// the function returns an error (not a partial result) so callers always get
+// either a complete view or a clear error signal.
 func (c *Client) GetCommitStatuses(ctx context.Context, owner, repo, sha string) ([]vcs.CommitStatus, error) {
 	var result []vcs.CommitStatus
 
@@ -192,7 +195,7 @@ func mapCheckRunStatus(conclusion *string) string {
 	case "failure", "action_required", "timed_out":
 		return "failure"
 	case "cancelled", "skipped", "neutral":
-		return "success" // non-blocking
+		return "success" // non-blocking: these do not indicate a blocking failure per GitHub check suite semantics
 	case "stale", "waiting":
 		return "pending"
 	default: