So i accidentaly picked up a grave with the mod Carry On, and says it was destroyed, but it still remains in the player's hand. When it comes back to the ground, you can still get your itens from it, although it becomes indestructible. Dont know if i desinstall the mod it will crash my world or just vanish and what can i do to resolve the situation.

The only way I have find is to change to creative and destroy it

Oh sorry I didn't realize I never replied to this issue. Unfortunately, no you can't break it in survival if this happens. I'll get an update out eventually that fixes this issue. How long it will be until it's released depends on how much time I can spend on modding. Hopefully I'll get it released within the coming week, but it could very well be delayed by yet another month.