fix empty playlist adding to offline catalog

app/src/main/java/ru/vtosters/lite/music/cache/CacheDatabaseDelegate.java

@@ -235,6 +235,10 @@ public class CacheDatabaseDelegate {
         return null; // get playlist from db
     }
 
+    public static boolean hasPlaylist() {
+        return false; // has playlists or not
+    }
+
     public static List<MusicTrack> getTracks(String query) {
         List<MusicTrack> list = new ArrayList<>();
         try (Cursor cursor = getHelper().getReadableDatabase().rawQuery(query, new String[0])) {

app/src/main/java/ru/vtosters/lite/music/cache/injectors/TracklistInjector.java

@@ -235,11 +235,15 @@ public class TracklistInjector {
 
         audiosBlock.put("layout", layout);
 
-        var blocks = new JSONArray()
-                .put(getCatalogHeader())
-                .put(getCatalogPlaylist())
-                .put(getCatalogSeparator())
-                .put(getShuffleButton())
+        var blocks = new JSONArray();
+
+        if (CacheDatabaseDelegate.hasPlaylist()) {
+            blocks.put(getCatalogHeader())
+                    .put(getCatalogPlaylist())
+                    .put(getCatalogSeparator());
+        }
+
+        blocks.put(getShuffleButton())
                 .put(audiosBlock);
 
         var randomId = getRandomId();