Crash

/* TeleportBlock.class */
package me.robert.teleport.blocks;

import me.robert.teleport.Teleport;
import me.robert.teleport.blocks.tileentities.TileEntityTeleport;
import me.robert.teleport.init.ModItems;
import net.minecraft.block.Block;
import net.minecraft.block.material.Material;
import net.minecraft.block.state.IBlockState;
import net.minecraft.entity.Entity;
import net.minecraft.entity.player.EntityPlayer;
import net.minecraft.item.Item;
import net.minecraft.item.ItemStack;
import net.minecraft.nbt.NBTTagCompound;
import net.minecraft.tileentity.TileEntity;
import net.minecraft.util.BlockPos;
import net.minecraft.world.World;

public class BlockTeleport extends Block {

    public BlockTeleport() {
        super(Material.rock);
        setCreativeTab(Teleport.tabTeleport);
    }

    @Override
    public void onLanded(World worldIn, Entity entityIn) {
        TileEntityTeleport tile = (TileEntityTeleport) worldIn.getTileEntity(entityIn.getPosition());
        if (tile != null) {
            int dim = tile.dim;
            int posX = tile.posX;
            int posY = tile.posY;
            int posZ = tile.posZ;

            entityIn.travelToDimension(dim);
            entityIn.setPositionAndUpdate(posX, posY, posZ);
        }
    }

    @Override
    public TileEntity createTileEntity(World world, IBlockState state) {
        return new TileEntityTeleport();
    }
}

/* TileEntityTeleport.class */
package me.robert.teleport.blocks.tileentities;

import net.minecraft.nbt.NBTTagCompound;
import net.minecraft.tileentity.TileEntity;

public class TileEntityTeleport extends TileEntity {

    public int dim;
    public int posX;
    public int posY;
    public int posZ;

    @Override
    public void writeToNBT(NBTTagCompound compound) {
        super.writeToNBT(compound);
        compound.setInteger("dim", dim);
        compound.setInteger("posX", posX);
        compound.setInteger("posY", posY);
        compound.setInteger("posZ", posZ);
    }

    @Override
    public void readFromNBT(NBTTagCompound compound) {
        super.readFromNBT(compound);
        compound.getInteger("dim");
        compound.getInteger("posX");
        compound.getInteger("posY");
        compound.getInteger("posZ");
    }
}

/* ItemCoordCache.class */
package me.robert.teleport.items;

import java.util.List;

import org.lwjgl.input.Keyboard;

import me.robert.teleport.blocks.tileentities.TileEntityTeleport;
import me.robert.teleport.init.ModBlocks;
import net.minecraft.client.gui.GuiScreen;
import net.minecraft.entity.player.EntityPlayer;
import net.minecraft.item.Item;
import net.minecraft.item.ItemStack;
import net.minecraft.nbt.NBTTagCompound;
import net.minecraft.util.BlockPos;
import net.minecraft.util.ChatComponentText;
import net.minecraft.util.EnumChatFormatting;
import net.minecraft.util.EnumFacing;
import net.minecraft.util.IChatComponent;
import net.minecraft.world.World;
import net.minecraft.world.WorldProvider;
import net.minecraftforge.fml.relauncher.Side;
import net.minecraftforge.fml.relauncher.SideOnly;

public class ItemCoordCache extends Item {

    @Override
    public boolean onItemUse(ItemStack stack, EntityPlayer playerIn, World worldIn, BlockPos pos, EnumFacing side, float hitX, float hitY, float hitZ) {

        if (!playerIn.isSneaking()) {
            if (stack.getTagCompound() == null) {
                stack.setTagCompound(new NBTTagCompound());
                NBTTagCompound nbt = new NBTTagCompound();
                nbt.setInteger("dim", playerIn.dimension);
                nbt.setInteger("posX", pos.getX());
                nbt.setInteger("posY", pos.getY());
                nbt.setInteger("posZ", pos.getZ());
                stack.getTagCompound().setTag("coord", nbt);
                stack.setStackDisplayName(EnumChatFormatting.AQUA + "Coordanite Cache");
            } else {
                if (worldIn.getBlockState(pos).getBlock().equals(ModBlocks.block_teleport)) {
                    TileEntityTeleport tile = (TileEntityTeleport) worldIn.getTileEntity(pos);
                    NBTTagCompound nbt = stack.getTagCompound().getCompoundTag("coord");

                    tile.dim = nbt.getInteger("dim");
                    tile.posX = nbt.getInteger("posX");
                    tile.posY = nbt.getInteger("posY");
                    tile.posZ = nbt.getInteger("posZ");
                }
            }
        }
        return false;
    }

    @Override
    public ItemStack onItemRightClick(ItemStack itemStackIn, World worldIn, EntityPlayer playerIn) {

        if (playerIn.isSneaking()) {
            if (itemStackIn.getTagCompound() != null) {
                itemStackIn.getTagCompound().removeTag("coord");
                itemStackIn.clearCustomName();
            }
        }
        return itemStackIn;
    }

    @Override
    @SideOnly(Side.CLIENT)
    public void addInformation(ItemStack stack, EntityPlayer playerIn, List tooltip, boolean advanced) {
        if (stack.getTagCompound() != null) {
            if (stack.getTagCompound().hasKey("coord")) {
                NBTTagCompound nbt = (NBTTagCompound) stack.getTagCompound().getTag("coord");
                int dim = nbt.getInteger("dim");
                int posX = nbt.getInteger("posX");
                int posY = nbt.getInteger("posY");
                int posZ = nbt.getInteger("posZ");

                String aqua = EnumChatFormatting.AQUA + "";
                String purple = EnumChatFormatting.DARK_PURPLE + "";

                String dimName = WorldProvider.getProviderForDimension(dim).getDimensionName();

                if (GuiScreen.isShiftKeyDown()) {
                    tooltip.add(aqua + "Dim: " + purple + dimName);
                    tooltip.add(aqua + "X: " + purple + posX);
                    tooltip.add(aqua + "Y: " + purple + posY);
                    tooltip.add(aqua + "Z: " + purple + posZ);
                } else {
                    tooltip.add(aqua + "Hold SHIFT for more information");
                }
            }
        }
    }

    @Override
    public boolean hasEffect(ItemStack stack) {
        if (stack.getTagCompound() != null) {
            return stack.getTagCompound().hasKey("coord");
        }
        return false;
    }
}