handle Loader.Load return value error

config/config.go

@@ -43,11 +43,11 @@ type Option func(o *Options)
 
 var (
 	// Default Config Manager
-	DefaultConfig = NewConfig()
+	DefaultConfig, _ = NewConfig()
 )
 
 // NewConfig returns new config
-func NewConfig(opts ...Option) Config {
+func NewConfig(opts ...Option) (Config, error) {
 	return newConfig(opts...)
 }
 

config/default.go

@@ -30,7 +30,7 @@ type watcher struct {
 	value reader.Value
 }
 
-func newConfig(opts ...Option) Config {
+func newConfig(opts ...Option) (Config, error) {
 	options := Options{
 		Loader: memory.NewLoader(),
 		Reader: json.NewReader(),
@@ -40,7 +40,10 @@ func newConfig(opts ...Option) Config {
 		o(&options)
 	}
 
-	options.Loader.Load(options.Source...)
+	if err := options.Loader.Load(options.Source...); err != nil {
+		return nil, err
+	}
+
 	snap, _ := options.Loader.Snapshot()
 	vals, _ := options.Reader.Values(snap.ChangeSet)
 
@@ -53,7 +56,7 @@ func newConfig(opts ...Option) Config {
 
 	go c.run()
 
-	return c
+	return c, nil
 }
 
 func (c *config) run() {

config/default_test.go

@@ -55,7 +55,10 @@ func TestConfigLoadWithGoodFile(t *testing.T) {
 	}()
 
 	// Create new config
-	conf := NewConfig()
+	conf, err := NewConfig()
+	if err != nil {
+		t.Fatalf("Expected no error but got %v", err)
+	}
 	// Load file source
 	if err := conf.Load(file.NewSource(
 		file.WithPath(path),
@@ -73,9 +76,12 @@ func TestConfigLoadWithInvalidFile(t *testing.T) {
 	}()
 
 	// Create new config
-	conf := NewConfig()
+	conf, err := NewConfig()
+	if err != nil {
+		t.Fatalf("Expected no error but got %v", err)
+	}
 	// Load file source
-	err := conf.Load(file.NewSource(
+	err = conf.Load(file.NewSource(
 		file.WithPath(path),
 		file.WithPath("/i/do/not/exists.json"),
 	))
@@ -105,13 +111,18 @@ func TestConfigMerge(t *testing.T) {
 	}()
 	os.Setenv("AMQP_HOST", "rabbit.testing.com")
 
-	conf := NewConfig()
-	conf.Load(
+	conf, err := NewConfig()
+	if err != nil {
+		t.Fatalf("Expected no error but got %v", err)
+	}
+	if err := conf.Load(
 		file.NewSource(
 			file.WithPath(path),
 		),
 		env.NewSource(),
-	)
+	); err != nil {
+		t.Fatalf("Expected no error but got %v", err)
+	}
 
 	actualHost := conf.Get("amqp", "host").String("backup")
 	if actualHost != "rabbit.testing.com" {