incorporate parsed options

lib/tasks/tts-task.js

@@ -89,8 +89,9 @@ class TtsTask extends Task {
     // api_key, model_id, api_uri, custom_tts_streaming_url, and auth_token are encoded in the credentials
     // allow them to be overriden via config, using options
     // give preference to options passed in via config
-    const local_options = {...JSON.parse(options), ...this.options};
-    const local_voice_settings = {...JSON.parse(options).voice_settings, ...this.options.voice_settings};
+    const parsed_options = JSON.parse(options ?? '{}');
+    const local_options = {...parsed_options, ...this.options ?? {}};
+    const local_voice_settings = {...parsed_options.voice_settings ?? {}, ...this.options?.voice_settings ?? {}};
     const local_api_key =  local_options.api_key ?? api_key;
     const local_model_id = local_options.model_id ?? model_id;
     const local_api_uri = local_options.api_uri ?? api_uri;