I decided to gift a ship to a vassal so he could be useful...
Upon gifting it CTD,,, Part of the crash may be due to him being a landlocked state. He has access to the sea via culture, but no actuall port cities. Was hoping to gift him his own navy...guess that broke the game.
The ship was the upgrade from Transport... Diesel Tank Transport Ship......????
Gifted untils always go to the capital, or (for sea units when capital land-locked) a coastal city. It probably doesn't check for the case of not having been able to find any such city and crashes. I'm sure that's easy to fix, but the simple fix will just lead to such units vanishing. A more complex fix that puts them somewhere other than in a city if no useful city exists will be a bit harder, but I'll see what I can do