diff --git a/github/client.go b/github/client.go
index 7f5c7f9..1555b34 100644
--- a/github/client.go
+++ b/github/client.go
@@ -47,6 +47,13 @@ func (e *APIError) Error() string {
 	return fmt.Sprintf("HTTP %d: %s", e.StatusCode, body)
 }
 
+// SafeError returns the error string without response body content,
+// suitable for logging in contexts where upstream response data should
+// not be exposed.
+func (e *APIError) SafeError() string {
+	return fmt.Sprintf("HTTP %d", e.StatusCode)
+}
+
 // IsNotFound reports whether an error is an API 404 response.
 func IsNotFound(err error) bool {
 	if apiErr, ok := asAPIError(err); ok {
@@ -172,6 +179,12 @@ func (c *Client) SetHTTPClient(hc *http.Client) {
 			Timeout:       30 * time.Second,
 			CheckRedirect: defaultCheckRedirect,
 		}
+	} else if hc.CheckRedirect == nil {
+		// Enforce safe redirect policy when caller provides a client without one.
+		// The default net/http behavior follows up to 10 redirects and forwards
+		// all headers (including Authorization) to any host, which can leak
+		// credentials on cross-host redirects.
+		hc.CheckRedirect = defaultCheckRedirect
 	}
 	c.httpClient = hc
 }
@@ -252,10 +265,11 @@ func (c *Client) doRequest(ctx context.Context, method, reqURL string, accept st
 
 		resp, err := c.httpClient.Do(req)
 		if err != nil {
+			// Transport errors (DNS, TLS, timeout) yield nil resp; no body to close.
 			return nil, fmt.Errorf("do request: %w", err)
 		}
 
-		body, done, err := c.handleResponse(resp, maxResponseBytes, maxErrorBodyBytes)
+		body, done, err := handleResponse(resp, maxResponseBytes, maxErrorBodyBytes)
 		if done {
 			return body, err
 		}
@@ -300,7 +314,7 @@ func (c *Client) doRequest(ctx context.Context, method, reqURL string, accept st
 // handleResponse reads and closes the response body, returning the result.
 // It uses defer to ensure the body is always closed regardless of code path.
 // Returns (body, done, err) where done=true means the caller should return immediately.
-func (c *Client) handleResponse(resp *http.Response, maxRespBytes int, maxErrBytes int) ([]byte, bool, error) {
+func handleResponse(resp *http.Response, maxRespBytes int, maxErrBytes int) ([]byte, bool, error) {
 	defer resp.Body.Close()
 
 	if resp.StatusCode >= 200 && resp.StatusCode < 300 {
diff --git a/github/client_test.go b/github/client_test.go
index a8ccc06..f1ccfcd 100644
--- a/github/client_test.go
+++ b/github/client_test.go
@@ -554,3 +554,46 @@ func TestSetHTTPClient_NilRestoresDefault(t *testing.T) {
 		t.Fatal("expected CheckRedirect policy after SetHTTPClient(nil)")
 	}
 }
+
+func TestSetHTTPClient_NilCheckRedirectEnforcesDefault(t *testing.T) {
+	c := NewClient("token", "https://api.github.com")
+	// Provide a client with nil CheckRedirect — should get default policy enforced.
+	hc := &http.Client{Timeout: 5 * time.Second}
+	c.SetHTTPClient(hc)
+	if c.httpClient.CheckRedirect == nil {
+		t.Fatal("expected CheckRedirect to be enforced when caller provides nil")
+	}
+	if c.httpClient.Timeout != 5*time.Second {
+		t.Errorf("expected caller's timeout preserved, got %v", c.httpClient.Timeout)
+	}
+}
+
+func TestSetHTTPClient_PreservesCustomCheckRedirect(t *testing.T) {
+	c := NewClient("token", "https://api.github.com")
+	called := false
+	hc := &http.Client{
+		CheckRedirect: func(req *http.Request, via []*http.Request) error {
+			called = true
+			return nil
+		},
+	}
+	c.SetHTTPClient(hc)
+	// Invoke the redirect to verify original is preserved
+	_ = c.httpClient.CheckRedirect(nil, []*http.Request{{}})
+	if !called {
+		t.Fatal("expected custom CheckRedirect to be preserved")
+	}
+}
+
+func TestAPIError_SafeError(t *testing.T) {
+	e := &APIError{StatusCode: 403, Body: "some sensitive body content"}
+	got := e.SafeError()
+	if got != "HTTP 403" {
+		t.Errorf("SafeError() = %q, want %q", got, "HTTP 403")
+	}
+	// Ensure Error() still includes body
+	full := e.Error()
+	if full != "HTTP 403: some sensitive body content" {
+		t.Errorf("Error() = %q, unexpected", full)
+	}
+}
diff --git a/github/files.go b/github/files.go
index 9f04941..bb301f0 100644
--- a/github/files.go
+++ b/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: as array: %v; as object: %w", err, err2)
+			return nil, fmt.Errorf("parse contents JSON: as array: %w; as object: %w", err, err2)
 		}
 		// Guard against empty objects ({}) or unexpected shapes that
 		// unmarshal successfully but carry no useful data.