Make lifecycle update tts name setter optional

Author: crokita

examples/js/hello-sdl/SDL.min.js

@@ -235,9 +235,12 @@ class SdlManager extends _SdlManagerBase {
                     .setHmiDisplayLanguage(actualLanguage)
                     .setAppName(lifecycleConfigUpdate.getAppName())
                     .setNgnMediaScreenAppName(lifecycleConfigUpdate.getShortAppName())
-                    .setTtsName(lifecycleConfigUpdate.getTtsName())
                     .setVrSynonyms(lifecycleConfigUpdate.getVoiceRecognitionCommandNames());
 
+                if (lifecycleConfigUpdate.getTtsName() !== null) {
+                    changeRegistration.setTtsName(lifecycleConfigUpdate.getTtsName());
+                }
+
                 this.sendRpc(changeRegistration)
                     .then((response) => {
                         this._lifecycleConfig.setLanguageDesired(actualLanguage);