fixed bug that made window crash when there were no playlists

src/widgets/main_view.vala

@@ -86,11 +86,13 @@ namespace Song {
 
             var config = Config.get_instance();
             config.config_changed.connect(() => {
-                if (config.playlists.length() == 1) {
-                    config.playlists.foreach((i) => {
-                        change_page(i);
-                        return;
-                    });
+                if (config.playlists != null) {
+                    if (config.playlists.length() == 1) {
+                        config.playlists.foreach((i) => {
+                            change_page(i);
+                            return;
+                        });
+                    }
                 }
             });
         }

src/widgets/playlist.vala

@@ -3,7 +3,7 @@ namespace Song {
 
         private Settings settings = new Settings ("com.liyaowhen.Song");
         
-        private PlaylistObject playlist;
+        public PlaylistObject playlist;
         private Gtk.Button remove_button;
         private Gtk.Revealer remove_button_revealer;
 
@@ -13,10 +13,17 @@ namespace Song {
         }
 
         construct {
+
+
             orientation = Gtk.Orientation.HORIZONTAL;
             add_css_class("toolbar");
             remove_button = new Gtk.Button.from_icon_name("app-remove-symbolic");
 
+            remove_button.clicked.connect(() => {
+                print("clicked");
+                confirm_delete_popup();
+            });
+
             remove_button_revealer = new Gtk.Revealer();
             remove_button_revealer.set_child(remove_button);
             remove_button_revealer.transition_type = Gtk.RevealerTransitionType.SWING_LEFT;
@@ -39,6 +46,7 @@ namespace Song {
                 if (playlist.name != null) {
                     main_button.label = playlist.name;
                 }
+
             });
 
             Config.get_instance().loaded.connect(() => {
@@ -60,5 +68,29 @@ namespace Song {
         public void exit_removal_mode() {
             remove_button_revealer.set_reveal_child(false);
         }
+
+        private void confirm_delete_popup() {
+            
+            
+            var alert_dialog = new Adw.AlertDialog("Remove Playlist?",
+            "Deleting a playlist is a non-reversable action,
+                however the playlist's items will remain intact in the configuration folder");
+            
+            alert_dialog.add_response("Cancel", "Cancel");
+            alert_dialog.add_response("Confirm", "Confirm");
+            alert_dialog.set_response_appearance("Confirm", Adw.ResponseAppearance.DESTRUCTIVE);
+
+            alert_dialog.present(this);
+
+            
+            alert_dialog.response.connect((i, e) => {
+                if (e == "Confirm") {
+                    Config.get_instance().playlists.remove(playlist);
+                    Config.get_instance().save.begin();
+                }
+            });
+            
+            
+        }
     }
 }

src/widgets/side_bar.vala

@@ -60,7 +60,7 @@ namespace Song {
             vexpand_set = true;
             hexpand_set = true;
 
-            PlaylistObject initial_playlist;
+            PlaylistObject? initial_playlist = null;
 
             /*var playlist_names = settings.get_strv("playlists");
             foreach (string _name in playlist_names) {
@@ -75,23 +75,33 @@ namespace Song {
             Config config = Config.get_instance();
             
             bool firstDeclared = false;
-            config.playlists.foreach((_playlist) => {
-                var button = new PlaylistButton(_playlist);
-                if (!firstDeclared) {initial_playlist = _playlist; firstDeclared = true;}
-
-                playlist_buttons.add(button);
-                append(button);
-            });
-
-            config.config_changed.connect(() => {
-                playlist_buttons.clear();
-                config.playlists.foreach((_playlist) => {
+            if (config.playlists != null) {
+                foreach (PlaylistObject _playlist in config.playlists) {
                     var button = new PlaylistButton(_playlist);
+                    if (!firstDeclared) {initial_playlist = _playlist; firstDeclared = true;}
     
                     playlist_buttons.add(button);
                     append(button);
-                });
-            });
+                }
+            }
+
+
+            print("\n aaaaaa" + playlist_buttons.size.to_string() + "\n");
+
+            config.config_changed.connect(() => {
+                foreach (PlaylistButton e in playlist_buttons) {
+                    print("\n" + e.playlist.name + "eee");
+                    e.destroy();
+                }
+                if (config.playlists != null) {
+                    config.playlists.foreach((_playlist) => {
+                        var button = new PlaylistButton(_playlist);
+        
+                        playlist_buttons.add(button);
+                        append(button);
+                    }); 
+                }
+            }); 
 
             Timeout.add(1000, () => {
                 if (playlist_buttons == null) {
@@ -105,9 +115,10 @@ namespace Song {
             //print("sidbar requesting main_view_content switch to playlist of name:\n" + playlists.nth_data(0).name);
             Timeout.add(1, () => {
                 if (SongController.main_view_content != null) {
-                    SongController.main_view_content.change_page(initial_playlist);
-                    return false;
-
+                    if (initial_playlist != null) {
+                        SongController.main_view_content.change_page(initial_playlist);
+                        return false;
+                    }
                 }
                 return true;
             }, 1);
@@ -163,16 +174,17 @@ namespace Song {
                         print("\n sidebar buttons are null");
                     }
                     if (i.get_active()) {
-                        sidebar_content.playlist_buttons.foreach((e) => {
+                        foreach (PlaylistButton e in sidebar_content.playlist_buttons) {
                             e.enter_removal_mode();
-                            print(e.name);
-                        });
+                            print(e.playlist.name);
+                        }
                     } else {
-                        sidebar_content.playlist_buttons.foreach((e) => {
+                        foreach (PlaylistButton e in sidebar_content.playlist_buttons) {
                             e.exit_removal_mode();
-                            print(e.name);
-                        });
+                            print(e.playlist.name);
+                        }
                     }
+                    print("\n" + sidebar_content.playlist_buttons.size.to_string() + "\n");
                 });