Remove listennotes request under fdroid.

lib/home/pocast_discovery.dart

@@ -197,6 +197,7 @@ class DiscoveryPageState extends State<DiscoveryPage> {
   }
 
   Future<List<OnlinePodcast>> _getTopPodcasts({int page}) async {
+    if(environment['apiKey'] == '') return [];
     final searchEngine = ListenNotesSearch();
     var searchResult = await searchEngine.fetchBestPodcast(
       genre: '',

lib/service/search_api.dart

@@ -24,9 +24,11 @@ class ListenNotesSearch {
   final _dio = Dio(BaseOptions(connectTimeout: 30000, receiveTimeout: 90000));
   final _baseUrl = "https://listen-api.listennotes.com/api/v2/";
   final _apiKey = environment['apiKey'];
+  bool get _validApi => _apiKey != '';
 
   Future<SearchPodcast<dynamic>> searchPodcasts(
       {String searchText, int nextOffset}) async {
+    if(!_validApi) return null;
     var url = "${_baseUrl}search?q="
         "${Uri.encodeComponent(searchText)}${"&sort_by_date=0&type=podcast&offset=$nextOffset"}";
     var response = await _dio.get(url,
@@ -41,6 +43,7 @@ class ListenNotesSearch {
 
   Future<SearchEpisodes<dynamic>> fetchEpisode(
       {String id, int nextEpisodeDate}) async {
+    if(!_validApi) return null;
     var url =
         "${_baseUrl}podcasts/$id?next_episode_pub_date=$nextEpisodeDate";
     var response = await _dio.get(url,
@@ -55,6 +58,7 @@ class ListenNotesSearch {
 
   Future<SearchTopPodcast<dynamic>> fetchBestPodcast(
       {String genre, int page, String region = 'us'}) async {
+    if(!_validApi) return null;
     var url =
         "${_baseUrl}best_podcasts?genre_id=$genre&page=$page&region=$region";
     var response = await Dio().get(url,