Add check for item entries when calculating unspecified durations

src/components/filemanager/Playlists.vue

@@ -207,6 +207,10 @@ export default {
     },
 
     unknownDurationCount({ item }) {
+      if (!item.entries) {
+        return 0
+      }
+
       return item.entries.filter(entry => !entry.duration).length;
     }
   },