The item given to the player disappears

[Hubmac]

Hi there i have problem with my mod. I create this mod for learning forge. Mod adds new item to minecraft and in the overided method "OnBlockDestroyed" i give to player 2 diamonds but when i click on this item in inventory dissapear or when i drop this item.

 

Code: 

package com.example.examplemod;

import net.minecraft.block.BlockState;
import net.minecraft.client.Minecraft;
import net.minecraft.client.entity.player.ClientPlayerEntity;
import net.minecraft.entity.LivingEntity;
import net.minecraft.entity.player.PlayerEntity;
import net.minecraft.item.Item;
import net.minecraft.item.ItemGroup;
import net.minecraft.item.ItemStack;
import net.minecraft.item.Items;
import net.minecraft.util.datafix.fixes.ItemStackUUID;
import net.minecraft.util.math.BlockPos;
import net.minecraft.world.World;
import net.minecraftforge.common.MinecraftForge;
import net.minecraftforge.common.ToolType;
import net.minecraftforge.fml.common.registry.GameRegistry;

public class Hammer extends Item {

    public Hammer() {
        super(new Item.Properties().group(ItemGroup.TOOLS).maxStackSize(4).addToolType(ToolType.AXE, 3).defaultMaxDamage(100).maxDamage(200));
    }

    @Override
    public boolean onBlockDestroyed(ItemStack itemStack, World world, BlockState blockState, BlockPos blockPos, LivingEntity livingEntity) {
        ClientPlayerEntity clientPlayerEntity = Minecraft.getInstance().player;


        clientPlayerEntity.sendChatMessage("You destroy: "+ blockState.getBlock().getRegistryName());
        clientPlayerEntity.inventory.addItemStackToInventory(new ItemStack(Items.DIAMOND, 2));

        return super.onBlockDestroyed(itemStack, world, blockState, blockPos, livingEntity);
    }
}

[Hubmac]

12 minutes ago, diesieben07 said:

You are reaching across logical sides. You need to use the living entity given to you and also check World#isRemote to ensure you only modify the inventory on the server.

Ok thanks, it works. I still have a question, how can I download "ServerPlayerEntity" in my case I convert "LivingEntity" to "ServerPlayerEntity" but is there any way to get "ServerPlayerEntity" from anywhere