update config parsing

pkg/registry/registry.go

@@ -1,6 +1,8 @@
 package registry
 
 import (
+	"errors"
+
 	"github.com/go-gost/gost/pkg/connector"
 	"github.com/go-gost/gost/pkg/dialer"
 	"github.com/go-gost/gost/pkg/handler"
@@ -8,6 +10,11 @@ import (
 	"github.com/go-gost/gost/pkg/logger"
 )
 
+var (
+	ErrDup      = errors.New("registry: duplicate instance")
+	ErrNotFound = errors.New("registry: instance not found")
+)
+
 type NewListener func(opts ...listener.Option) listener.Listener
 type NewHandler func(opts ...handler.Option) handler.Handler
 type NewDialer func(opts ...dialer.Option) dialer.Dialer