It's something I need to take a look into more if I'm honest, I checked all my media in VLC looking for duration and replaced any with no duration that wouldn't play.

I've got an old backup I can refer to and when I sync to my Synology the deleted items don't get removed so if something gets removed by mistake I have a couple of places to refer back to.

There's still the risk of ongoing corruption/bit rot so I installed Checkrr last weekend to try to flag problematic files.

Take a look: Checkrr