Crash when deleting a video

Description

When deleting a video, VLC crashes and restart. Here is the exception in logcat : java.lang.NullPointerException: Attempt to invoke virtual method 'void org.videolan.medialibrary.interfaces.media.MediaWrapper.removeThumbnail()' on a null object reference at org.videolan.vlc.viewmodels.CallBackDelegate.deleteThumbnail(CallBackDelegate.kt:133)

It happens since !1766 (merged). That's probably because in OnMediaDeleted, the media is already deleted, so medialibrary.getMedia will return null.

Steps to reproduce

1. Just delete a video

Context

App version

Latest master

Android version

Android 10 / 13

Device model

Sony Xperia XZ2 / Samsung Tab S7FE