service.go

@@ -103,6 +103,9 @@ func NewWithFS(fsys fs.FS, dir string, opts ...Option) (*Service, error) {
 
 // NewWithLoader creates a new i18n service with a custom loader.
 func NewWithLoader(loader Loader, opts ...Option) (*Service, error) {
+	if loader == nil {
+		return nil, log.E("NewWithLoader", "nil loader", nil)
+	}
 	s := &Service{
 		loader:          loader,
 		messages:        make(map[string]map[string]Message),
@@ -836,6 +839,9 @@ func (s *Service) AddMessages(lang string, messages map[string]string) {
 // and grammar data into the existing service. This is the correct way to
 // add package-specific translations at runtime.
 func (s *Service) AddLoader(loader Loader) error {
+	if loader == nil {
+		return log.E("Service.AddLoader", "nil loader", nil)
+	}
 	langs := loader.Languages()
 	for _, lang := range langs {
 		messages, grammar, err := loader.Load(lang)

service_test.go

@@ -986,6 +986,17 @@ func TestServiceAddLoader_Bad(t *testing.T) {
 	}
 }
 
+func TestServiceAddLoader_Nil(t *testing.T) {
+	svc, err := New()
+	if err != nil {
+		t.Fatalf("New() failed: %v", err)
+	}
+
+	if err := svc.AddLoader(nil); err == nil {
+		t.Error("AddLoader() should fail with nil loader")
+	}
+}
+
 func TestPackageLevelAddLoader(t *testing.T) {
 	svc, err := New()
 	if err != nil {
@@ -1047,6 +1058,12 @@ func TestNewWithLoaderNoLanguages(t *testing.T) {
 	}
 }
 
+func TestNewWithLoaderNil(t *testing.T) {
+	if _, err := NewWithLoader(nil); err == nil {
+		t.Error("NewWithLoader(nil) should fail")
+	}
+}
+
 func TestServiceIsRTL(t *testing.T) {
 	svc, err := New()
 	if err != nil {