Unregister ML callbacks before cancelling tasks

vlc-android/src/org/videolan/vlc/viewmodels/MedialibraryModel.kt

@@ -44,7 +44,7 @@ abstract class MedialibraryModel<T : MediaLibraryItem>(context: Context) : BaseM
     }
 
     override fun onCleared() {
-        super.onCleared()
         medialibrary.removeOnMedialibraryReadyListener(this)
+        super.onCleared()
     }
 }
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