Fix local DNS server crash

dns/transport/local/local_resolved_linux.go

@@ -11,6 +11,7 @@ import (
 	C "github.com/sagernet/sing-box/constant"
 	"github.com/sagernet/sing-box/service/resolved"
 	"github.com/sagernet/sing-tun"
+	"github.com/sagernet/sing/common"
 	"github.com/sagernet/sing/common/control"
 	E "github.com/sagernet/sing/common/exceptions"
 	"github.com/sagernet/sing/common/logger"
@@ -82,7 +83,7 @@ func (t *DBusResolvedResolver) Close() error {
 }
 
 func (t *DBusResolvedResolver) Object() any {
-	return t.resoledObject.Load()
+	return common.PtrOrNil(t.resoledObject.Load())
 }
 
 func (t *DBusResolvedResolver) Exchange(object any, ctx context.Context, message *mDNS.Msg) (*mDNS.Msg, error) {