Fix crash when sorting albums with a null artist

app/src/main/java/com/cappielloantonio/tempo/ui/adapter/AlbumCatalogueAdapter.java

@@ -157,7 +157,7 @@ public class AlbumCatalogueAdapter extends RecyclerView.Adapter<AlbumCatalogueAd
                 albums.sort(Comparator.comparing(AlbumID3::getName));
                 break;
             case Constants.ALBUM_ORDER_BY_ARTIST:
-                albums.sort(Comparator.comparing(AlbumID3::getArtist));
+                albums.sort(Comparator.comparing(AlbumID3::getArtist, Comparator.nullsLast(Comparator.naturalOrder())));
                 break;
             case Constants.ALBUM_ORDER_BY_YEAR:
                 albums.sort(Comparator.comparing(AlbumID3::getYear));

app/src/main/java/com/cappielloantonio/tempo/ui/fragment/PlaylistPageFragment.java

@@ -140,11 +140,6 @@ public class PlaylistPageFragment extends Fragment implements ClickCallback {
                 }
             });
             return true;
-        } else if (item.getItemId() == R.id.action_add_to_queue) {
-            playlistPageViewModel.getPlaylistSongLiveList().observe(getViewLifecycleOwner(), songs -> {
-                MediaManager.enqueue(mediaBrowserListenableFuture, songs, false);
-            });
-            return true;
         } else if (item.getItemId() == R.id.action_pin_playlist) {
             playlistPageViewModel.setPinned(true);
             return true;

app/src/main/res/menu/playlist_page_menu.xml

@@ -13,13 +13,6 @@
         android:icon="@drawable/ic_file_download"
         android:title="@string/menu_download_all_button"
         app:showAsAction="never" />
-
-    <item
-        android:id="@+id/action_add_to_queue"
-        android:icon="@drawable/ic_add"
-        android:title="@string/menu_add_to_queue_button"
-        app:showAsAction="never" />
-
     <item
         android:id="@+id/action_pin_playlist"
         android:icon="@drawable/ic_add"

app/src/main/res/values/strings.xml

@@ -157,7 +157,6 @@
     <string name="login_title">Subsonic servers</string>
     <string name="login_title_expanded">Subsonic servers</string>
     <string name="media_route_menu_title">Cast</string>
-    <string name="menu_add_to_queue_button">Add to queue</string>
     <string name="menu_add_button">Add</string>
     <string name="menu_download_all_button">Download all</string>
     <string name="menu_download_label">Download</string>