fix: Item stack resurrection causing incorrect internal state of Lith…

…iumStackList

Caused missing comparator updates and maybe a lot more, other issues

src/main/java/me/jellysquid/mods/lithium/common/hopper/LithiumStackList.java

@@ -116,6 +116,19 @@ public void changed() {
     @Override
     public ItemStack set(int index, ItemStack element) {
         ItemStack previous = super.set(index, element);
+
+        //Handle vanilla's item stack resurrection in HopperBlockEntity extract(Hopper hopper, Inventory inventory, int slot, Direction side):
+        // Item stacks are set to 0 items, then back to 1. Then inventory.set(index, element) is called.
+        // At this point, the LithiumStackList unsubscribed from the stack when it reached 0.
+        // Handle: If the previous == element, and the stack is not subscribed, we handle it as if an empty stack was replaced.
+        if (previous == element && !element.isEmpty()) {
+            //noinspection unchecked
+            boolean notSubscribed = ((ChangePublisher<ItemStack>) (Object) previous).lithium$isSubscribedWithData(this, index);
+            if (!notSubscribed)  {
+                previous = ItemStack.EMPTY;
+            }
+        }
+
         if (previous != element) {
             if (!previous.isEmpty()) {
                 //noinspection unchecked

src/main/java/me/jellysquid/mods/lithium/common/util/change_tracking/ChangePublisher.java

@@ -1,5 +1,7 @@
 package me.jellysquid.mods.lithium.common.util.change_tracking;
 
+import net.minecraft.item.ItemStack;
+
 public interface ChangePublisher<T> {
     void lithium$subscribe(ChangeSubscriber<T> subscriber, int subscriberData);
 
@@ -8,4 +10,8 @@ public interface ChangePublisher<T> {
     default void lithium$unsubscribeWithData(ChangeSubscriber<T> subscriber, int index) {
         throw new UnsupportedOperationException("Only implemented for ItemStacks");
     }
+
+    default boolean lithium$isSubscribedWithData(ChangeSubscriber<ItemStack> subscriber, int subscriberData) {
+        throw new UnsupportedOperationException("Only implemented for ItemStacks");
+    }
 }

src/main/java/me/jellysquid/mods/lithium/common/util/change_tracking/ChangeSubscriber.java

@@ -1,6 +1,7 @@
 package me.jellysquid.mods.lithium.common.util.change_tracking;
 
 import it.unimi.dsi.fastutil.ints.IntArrayList;
+import net.minecraft.item.ItemStack;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 
@@ -79,6 +80,13 @@ static int dataOf(ChangeSubscriber<?> subscribers, ChangeSubscriber<?> subscribe
         return subscribers instanceof Multi<?> multi ? multi.subscriberDatas.getInt(multi.subscribers.indexOf(subscriber)) : subscriberData;
     }
 
+    static boolean containsSubscriber(ChangeSubscriber<ItemStack> subscriber, int subscriberData, ChangeSubscriber<ItemStack> subscriber1, int subscriberData1) {
+        if (subscriber instanceof Multi<ItemStack> multi) {
+            return multi.indexOf(subscriber1, subscriberData1, true) != -1;
+        }
+        return subscriber == subscriber1 && subscriberData == subscriberData1;
+    }
+
 
     /**
      * Notify the subscriber that the publisher will be changed immediately after this call.

src/main/java/me/jellysquid/mods/lithium/mixin/util/inventory_comparator_tracking/BlockEntityMixin.java

@@ -46,7 +46,7 @@ private void init(BlockEntityType<?> type, BlockPos pos, BlockState state, Callb
     public void lithium$onComparatorAdded(Direction direction, int offset) {
         byte hasComparators = this.hasComparators;
         if (direction.getAxis() != Direction.Axis.Y && hasComparators != COMPARATOR_PRESENT && offset >= 1 && offset <= 2) {
-            this.hasComparators = 1;
+            this.hasComparators = COMPARATOR_PRESENT;
 
             if (this instanceof InventoryChangeTracker inventoryChangeTracker) {
                 inventoryChangeTracker.lithium$emitFirstComparatorAdded();

src/main/java/me/jellysquid/mods/lithium/mixin/util/item_component_and_count_tracking/ItemStackMixin.java

@@ -83,6 +83,15 @@ public abstract class ItemStackMixin implements ChangePublisher<ItemStack>, Chan
         }
     }
 
+    @Override
+    public boolean lithium$isSubscribedWithData(ChangeSubscriber<ItemStack> subscriber, int subscriberData) {
+        if (this.isEmpty()) {
+            throw new IllegalStateException("Cannot be subscribed to an empty ItemStack!");
+        }
+
+        return ChangeSubscriber.containsSubscriber(this.subscriber, this.subscriberData, subscriber, subscriberData);
+    }
+
     @Override
     public void lithium$forceUnsubscribe(ComponentMapImpl publisher, int subscriberData) {
         if (publisher != this.components) {