Logging middleware: fix invalid memory address panic if response is nil (#471)

panic: runtime error: invalid memory address or nil pointer dereference [recovered, repanicked]
[signal SIGSEGV: segmentation violation code=0x2 addr=0x38 pc=0x102840ad4]

Author: andygrunwald

githubapp/middleware_logging.go

@@ -86,13 +86,14 @@ func ClientLogging(lvl zerolog.Level, opts ...ClientLoggingOption) ClientMiddlew
 				} else {
 					evt.Int64("size", size)
 				}
+
+				addRateLimitInformationToLog(options.LogRateLimitInformation, evt, res)
 			} else {
 				evt.Bool("cached", false).
 					Int("status", -1).
 					Int64("size", -1)
 			}
 
-			addRateLimitInformationToLog(options.LogRateLimitInformation, evt, res)
 			evt.Msg("github_request")
 			return res, err
 		})

githubapp/middleware_logging_test.go

@@ -123,6 +123,27 @@ func TestClientLogging(t *testing.T) {
 			"response_body": missingField,
 		})
 	})
+
+	t.Run("nilRequest", func(t *testing.T) {
+		req, _ := newLoggingRequest("GET", "https://test.domain/path", []byte("The request"))
+		rt := newEmptyRoundTripper()
+
+		logMiddleware := ClientLogging(zerolog.InfoLevel, LogRateLimitInformation(&RateLimitLoggingOption{
+			Limit:     true,
+			Remaining: true,
+			Used:      true,
+			Reset:     true,
+			Resource:  true,
+		}))
+		rt = logMiddleware(rt)
+
+		_, err := rt.RoundTrip(req)
+		if err != nil {
+			t.Fatalf("unexpected error making request: %v", err)
+		}
+
+		// To ensure that this is not crashing
+	})
 }
 
 func newLoggingRequest(method, url string, body []byte) (*http.Request, *bytes.Buffer) {
@@ -158,6 +179,12 @@ func newStaticRoundTripper(status int, body []byte) http.RoundTripper {
 	})
 }
 
+func newEmptyRoundTripper() http.RoundTripper {
+	return roundTripperFunc(func(r *http.Request) (*http.Response, error) {
+		return nil, nil
+	})
+}
+
 var missingField struct{}
 
 func assertLogFields(t *testing.T, out []byte, expected map[string]interface{}) {