Hello, I was testing something and when I tried to evolve a Staryu I got this error after the evolution sequence:
Then I tried again with a Weepinbell and the same happened. It didn't happen when I used a Rare Candy on a Magikarp, so I think it's only the stones. I even removed the lines I added myself to PokemonItemEffects so I don't know what the problem is.
The problem is that you're upgrading backwards. How do you expect to know exactly what needs taking from the latest version of Essentials and put into your game? Conversely, you should have been making notes about exactly what you've been adding to your game.
It's easier, safer and more reliable to add your game's features to the latest Essentials than it is to try extracting the updates from the latest Essentials and bundle them into your game.
Oh no, that's what I'm doing, I imported all my changes from ver11 (skipped v12) into v13. And added a "#comment" in every script I modify. When I said I copied the script from v13 I meant an unmodified backup.
I think the problem was I didn't do this for PokemonParty because I thought there were no significant changes and just copied the whole script. Believe me I won't do that again xD