SPIGOT-7389: Handle setting null items in ChiseledBookshelf Inventory

By: Doc <nachito94@msn.com>

paper-server/nms-patches/net/minecraft/world/level/block/entity/ChiseledBookShelfBlockEntity.patch

@@ -63,6 +63,15 @@
          this.items.clear();
          ContainerUtil.loadAllItems(nbttagcompound, this.items);
          this.lastInteractedSlot = nbttagcompound.getInt("last_interacted_slot");
+@@ -91,7 +134,7 @@
+ 
+         this.items.set(i, ItemStack.EMPTY);
+         if (!itemstack.isEmpty()) {
+-            this.updateState(i);
++            if (level != null) this.updateState(i); // CraftBukkit - SPIGOT-7381: check for null world
+         }
+ 
+         return itemstack;
 @@ -106,7 +149,7 @@
      public void setItem(int i, ItemStack itemstack) {
          if (itemstack.is(TagsItem.BOOKSHELF_BOOKS)) {

paper-server/src/main/java/org/bukkit/craftbukkit/inventory/CraftInventoryChiseledBookshelf.java

@@ -3,6 +3,7 @@ package org.bukkit.craftbukkit.inventory;
 import net.minecraft.world.level.block.entity.ChiseledBookShelfBlockEntity;
 import org.bukkit.block.ChiseledBookshelf;
 import org.bukkit.inventory.ChiseledBookshelfInventory;
+import org.bukkit.inventory.ItemStack;
 
 public class CraftInventoryChiseledBookshelf extends CraftInventory implements ChiseledBookshelfInventory {
 
@@ -11,6 +12,17 @@ public class CraftInventoryChiseledBookshelf extends CraftInventory implements C
 
     }
 
+    @Override
+    public void setItem(int index, ItemStack item) {
+        net.minecraft.world.item.ItemStack nms = CraftItemStack.asNMSCopy(item);
+
+        if (nms.isEmpty()) {
+            this.getInventory().removeItemNoUpdate(index);
+        } else {
+            this.getInventory().setItem(index, nms);
+        }
+    }
+
     @Override
     public ChiseledBookshelf getHolder() {
         return (ChiseledBookshelf) inventory.getOwner();