potioncore help

val pc_lingering = [
    <minecraft:lingering_potion>.withTag({Potion: "potioncore:wither"}),
    <minecraft:lingering_potion>.withTag({Potion: "potioncore:strong_wither"})
] as IItemStack;

val pc_splash = [
    <minecraft:splash_potion>.withTag({Potion: "potioncore:wither"}),
    <minecraft:splash_potion>.withTag({Potion: "potioncore:strong_wither"})
] as IItemStack;

for i, item in pc_lingering {
    brewing.addBrew(item, <minecraft:dragon_breath>, pc_splash[i]);
}