fix(log): redact named string types instead of panicking

The redaction hook matched fields by reflect.Kind but read them with a
v.(string) type assertion, so any named string type (such as an enum)
panicked the log call. API v1 problem logging hit this on every error.

log/redactrus.go

@@ -47,7 +47,8 @@ func (h *Hook) Fire(e *logrus.Entry) error {
 			}
 			switch reflect.TypeOf(v).Kind() {
 			case reflect.String:
-				e.Data[k] = re.ReplaceAllString(v.(string), "$1[REDACTED]$2")
+				// Via reflect: named string types (e.g. enums) have Kind String but fail v.(string).
+				e.Data[k] = re.ReplaceAllString(reflect.ValueOf(v).String(), "$1[REDACTED]$2")
 				continue
 			case reflect.Map:
 				s := fmt.Sprintf("%+v", v)

log/redactrus_test.go

@@ -157,3 +157,14 @@ func TestEntryMessage(t *testing.T) {
 	assert.Nil(t, err)
 	assert.Equal(t, "Secret Password: [REDACTED]", logEntry.Message)
 }
+
+type namedString string
+
+func TestFireRedactsNamedStringTypes(t *testing.T) {
+	hook := &Hook{RedactionList: []string{"(secret=)[^&]+"}}
+	e := &logrus.Entry{Data: logrus.Fields{"code": namedString("not_found"), "url": namedString("/x?secret=abc")}}
+
+	assert.NotPanics(t, func() { _ = hook.Fire(e) })
+	assert.Equal(t, "not_found", e.Data["code"])
+	assert.Equal(t, "/x?secret=[REDACTED]", e.Data["url"])
+}

server/apiv1/problem_test.go

@@ -77,6 +77,13 @@ var _ = Describe("problem", func() {
 			Expect(*p.Errors).To(ConsistOf(ValidationError{Field: "currentPassword", Message: "is incorrect"}))
 		})
 
+		It("writes and logs a problem with debug logging on", func() {
+			logs := captureLogs()
+			writeProblem(w, r, model.ErrNotFound)
+			Expect(w.Code).To(Equal(http.StatusNotFound))
+			Expect(logs.String()).To(ContainSubstring("code=not_found"))
+		})
+
 		It("adds a Bearer challenge to every 401 unless one is already set", func() {
 			writeProblem(w, r, model.ErrInvalidAuth)
 			Expect(w.Header().Get("WWW-Authenticate")).To(Equal("Bearer"))