Code Review Optimierungen: Typsicherheit, Scanner-Performance, DB Upgrade Template, Division Guard

lib/database/db_helper.dart

@@ -82,6 +82,9 @@ class DbHelper {
           )
         ''');
       },
+      onUpgrade: (db, oldVersion, newVersion) async {
+        // Hier zukünftige DB-Migrationen einpflegen (z.B. if (oldVersion < 2) ...)
+      },
     );
   }
 

lib/services/download_service.dart

@@ -100,7 +100,7 @@ class DownloadService {
         await for (final chunk in fileStream) {
           sink.add(chunk);
           downloaded += chunk.length;
-          _fortschritt = downloaded / total;
+          _fortschritt = total > 0 ? downloaded / total : 0.0;
         }
         await sink.flush();
         await sink.close();

lib/services/musik_scanner.dart

@@ -26,6 +26,8 @@ class MusikScanner {
     final gefunden = <Song>[];
     final pfade = await _sammleMusikPfade();
 
+    final player = AudioPlayer();
+
     for (final pfad in pfade) {
       try {
         final file = File(pfad);
@@ -35,7 +37,7 @@ class MusikScanner {
           titel: _dateiNameOhneEndung(pfad),
           kuenstler: 'Unbekannt',
           album: '',
-          dauerSekunden: await _ermittleDauer(pfad),
+          dauerSekunden: await _ermittleDauer(player, pfad),
           dateiPfad: pfad,
           coverPfad: null,
           groesseBytes: stat.size,
@@ -47,6 +49,10 @@ class MusikScanner {
       }
     }
 
+    try {
+      await player.dispose();
+    } catch (_) {}
+
     // In DB speichern
     final vorhandene = await _db.alleSongs();
     final vorhandenePfade = vorhandene.map((s) => s.dateiPfad).toSet();
@@ -126,12 +132,10 @@ class MusikScanner {
     } catch (_) {}
   }
 
-  Future<int> _ermittleDauer(String pfad) async {
+  Future<int> _ermittleDauer(AudioPlayer player, String pfad) async {
     try {
-      final player = AudioPlayer();
       await player.setFilePath(pfad);
       final dauer = player.duration;
-      await player.dispose();
       return dauer?.inSeconds ?? 0;
     } catch (_) {
       return 0;

lib/viewmodels/melo_home_viewmodel.dart

@@ -75,7 +75,6 @@ class MeloHomeViewModel extends ChangeNotifier {
 
     songs = alle;
     favoritenIds = await favoriten.favoritenIds();
-    tagCounts = _berechneTagCounts();
     letzteSongs = await db.letzteWiedergaben();
     await ladeTags();
     ladt = false;

lib/widgets/navidrome_browser.dart

@@ -1,11 +1,12 @@
 import 'package:flutter/material.dart';
 import '../services/navidrome_service.dart';
 import '../utils/farb_theme.dart';
+import '../viewmodels/melo_home_viewmodel.dart';
 
 /// Navidrome-Browser als Bottom-Sheet.
 /// Manuell in home_screen.dart einbaubar.
 class NavidromeBrowser extends StatefulWidget {
-  final dynamic vm;
+  final MeloHomeViewModel vm;
   const NavidromeBrowser({super.key, required this.vm});
 
   @override

lib/widgets/playlist_sheet.dart

@@ -2,10 +2,11 @@ import 'package:flutter/material.dart';
 import '../models/song.dart';
 import '../models/playlist.dart';
 import '../utils/farb_theme.dart';
+import '../viewmodels/melo_home_viewmodel.dart';
 
 /// Bottom-Sheet zum Durchstöbern von Playlists.
 class PlaylistSheet extends StatefulWidget {
-  final dynamic vm;
+  final MeloHomeViewModel vm;
   const PlaylistSheet({super.key, required this.vm});
 
   @override
@@ -174,7 +175,7 @@ class _PlaylistSheetState extends State<PlaylistSheet> {
 class _PlaylistDetail extends StatelessWidget {
   final Playlist p;
   final List<Song> songs;
-  final dynamic vm;
+  final MeloHomeViewModel vm;
   final VoidCallback onChanged;
 
   const _PlaylistDetail({