SPIGOT-7381: Fix NullPointerException when setting item in ChiseledBookshelfInventory snapshot

By: Parker Hawke <hawkeboyz2@hotmail.com>

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

@@ -55,6 +55,15 @@
  
      public ChiseledBookShelfBlockEntity(BlockPosition blockposition, IBlockData iblockdata) {
          super(TileEntityTypes.CHISELED_BOOKSHELF, blockposition, iblockdata);
+@@ -106,7 +148,7 @@
+     public void setItem(int i, ItemStack itemstack) {
+         if (itemstack.is(TagsItem.BOOKSHELF_BOOKS)) {
+             this.items.set(i, itemstack);
+-            this.updateState(i);
++            if (level != null) this.updateState(i); // CraftBukkit - SPIGOT-7381: check for null world
+         }
+ 
+     }
 @@ -120,7 +162,7 @@
  
      @Override