Saving entity NBT on Minecraft Server

Time: 7/11/21, 10:45 PMTime: 7/11/21, 10:45 PMDescription: Saving entity NBT
java.lang.NullPointerException: Cannot invoke "it.unimi.dsi.fastutil.objects.ObjectArrayList.get(int)" because "this.wrapped" is null at it.unimi.dsi.fastutil.objects.Object2ObjectOpenHashMap$MapIterator.nextEntry(Object2ObjectOpenHashMap.java:506) at it.unimi.dsi.fastutil.objects.Object2ObjectOpenHashMap$FastEntryIterator.next(Object2ObjectOpenHashMap.java:593) at it.unimi.dsi.fastutil.objects.Object2ObjectOpenHashMap$FastEntryIterator.next(Object2ObjectOpenHashMap.java:589) at app//net.minecraft.nbt.CompoundTag.copy(CompoundTag.java:396) at app//net.minecraft.world.item.ItemStack.save(ItemStack.java:486) at app//net.minecraft.world.entity.item.ItemEntity.addAdditionalSaveData(ItemEntity.java:363) at app//net.minecraft.world.entity.Entity.saveWithoutId(Entity.java:2124) at app//net.minecraft.world.entity.Entity.saveAsPassenger(Entity.java:2022) at app//net.minecraft.world.entity.Entity.save(Entity.java:2029) at app//net.minecraft.world.level.chunk.storage.EntityStorage.lambda$storeEntities$1(EntityStorage.java:106) at java.base/java.util.ArrayList$ArrayListSpliterator.forEachRemaining(ArrayList.java:1625) at java.base/java.util.stream.ReferencePipeline$Head.forEach(ReferencePipeline.java:762) at app//net.minecraft.world.level.chunk.storage.EntityStorage.storeEntities(EntityStorage.java:94) at app//net.minecraft.world.level.entity.PersistentEntitySectionManager.storeChunkSections(PersistentEntitySectionManager.java:284) at app//net.minecraft.world.level.entity.PersistentEntitySectionManager.processChunkUnload(PersistentEntitySectionManager.java:301) at app//net.minecraft.world.level.entity.PersistentEntitySectionManager.lambda$processUnloads$10(PersistentEntitySectionManager.java:319) at it.unimi.dsi.fastutil.longs.LongCollection.removeIf(LongCollection.java:197) at app//net.minecraft.world.level.entity.PersistentEntitySectionManager.processUnloads(PersistentEntitySectionManager.java:318) at app//net.minecraft.world.level.entity.PersistentEntitySectionManager.tick(PersistentEntitySectionManager.java:336) at app//net.minecraft.server.level.ServerLevel.tick(ServerLevel.java:863) at app//net.minecraft.server.MinecraftServer.tickChildren(MinecraftServer.java:1613) at app//net.minecraft.server.dedicated.DedicatedServer.tickChildren(DedicatedServer.java:482) at app//net.minecraft.server.MinecraftServer.tickServer(MinecraftServer.java:1465) at app//net.minecraft.server.MinecraftServer.runServer(MinecraftServer.java:1261) at app//net.minecraft.server.MinecraftServer.lambda$spin$0(MinecraftServer.java:317) at java.base/java.lang.Thread.run(Thread.java:831)