Help making smelting recipe

Im following a tutorial by a youtuber called Infernal Device, where you make recipes for converting rotten flesh into leather, I did have to do it slightly differently because his method wasnt working. While the datapack now works, my code is complaining that its wrong and I don't know why. Im using 1.21.4 with visual studio code with Datapack helper plus and syntax-mcfunction. Any help would be appreciated