I made orb maker.

but it was crash when i open GUI

Caused by: java.lang.NullPointerException
	at net.minecraftforge.items.SlotItemHandler.getStack(SlotItemHandler.java:62) ~[SlotItemHandler.class:?]
	at net.minecraft.inventory.Container.getInventory(Container.java:75) ~[Container.class:?]
	at net.minecraft.inventory.Container.addListener(Container.java:61) ~[Container.class:?]
	at net.minecraftforge.fml.common.network.internal.FMLNetworkHandler.openGui(FMLNetworkHandler.java:101) ~[FMLNetworkHandler.class:?]
	at net.minecraft.entity.player.EntityPlayer.openGui(EntityPlayer.java:2809) ~[EntityPlayer.class:?]
	at com.teamapplejuice.blocks.BlockOrbMaker.onBlockActivated(BlockOrbMaker.java:39) ~[BlockOrbMaker.class:?]
	at net.minecraft.server.management.PlayerInteractionManager.processRightClickBlock(PlayerInteractionManager.java:475) ~[PlayerInteractionManager.class:?]
	at net.minecraft.network.NetHandlerPlayServer.processTryUseItemOnBlock(NetHandlerPlayServer.java:767) ~[NetHandlerPlayServer.class:?]
	at net.minecraft.network.play.client.CPacketPlayerTryUseItemOnBlock.processPacket(CPacketPlayerTryUseItemOnBlock.java:68) ~[CPacketPlayerTryUseItemOnBlock.class:?]
	at net.minecraft.network.play.client.CPacketPlayerTryUseItemOnBlock.processPacket(CPacketPlayerTryUseItemOnBlock.java:13) ~[CPacketPlayerTryUseItemOnBlock.class:?]
	at net.minecraft.network.PacketThreadUtil$1.run(PacketThreadUtil.java:21) ~[PacketThreadUtil$1.class:?]
	at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511) ~[?:1.8.0_161]
	at java.util.concurrent.FutureTask.run(FutureTask.java:266) ~[?:1.8.0_161]
	at net.minecraft.util.Util.runTask(Util.java:53) ~[Util.class:?]
	... 5 more

public class BlockOrbMaker extends BlockBase implements ITileEntityProvider{

	public BlockOrbMaker() {
		super("orb_maker", Material.WOOD, 2, "axe", 0, 0);
		// TODO Auto-generated constructor stub
	}
	@Override
	public boolean onBlockActivated(World worldIn, BlockPos pos, IBlockState state, EntityPlayer playerIn,
			EnumHand hand, EnumFacing facing, float hitX, float hitY, float hitZ) {
		// TODO Auto-generated method stub
			playerIn.openGui(EpicStats.instance, GuiHandler.ORB_MAKER, worldIn, pos.getX(), pos.getY(), pos.getZ());
		return super.onBlockActivated(worldIn, pos, state, playerIn, hand, facing, hitX, hitY, hitZ);
	}
	@Override
	public TileEntity createNewTileEntity(World worldIn, int meta) {
		// TODO Auto-generated method stub
		return new TileEntityOrbMaker();
	}
}

public class GUIOrbMaker extends GuiContainer {
	private TileEntityOrbMaker te;

	public GUIOrbMaker(IInventory player, TileEntityOrbMaker orbMaker) {
		super(new ContainerOrbMaker(orbMaker, player));
		this.te = orbMaker;
		// TODO Auto-generated constructor stub
	}

	@Override
	protected void drawGuiContainerBackgroundLayer(float partialTicks, int mouseX, int mouseY) {
		// TODO Auto-generated method stub
		this.mc.getTextureManager().bindTexture(new ResourceLocation(Reference.MODID, "textures/gui/orbmaker.png"));
		this.drawTexturedModalRect(this.guiLeft, this.guiTop, 0, 0, this.xSize, this.ySize);

	}
}

class ContainerOrbMaker extends Container {
	private TileEntityOrbMaker te;
	public IItemHandler handler;

	public ContainerOrbMaker(TileEntityOrbMaker te, IInventory playerInv) {
		this.te = te;
		this.handler = te.getCapability(CapabilityItemHandler.ITEM_HANDLER_CAPABILITY, null); // Gets
																								// the
																								// inventory
																								// from
																								// our
																								// tile
																								// entity

		this.addSlotToContainer(new SlotItemHandler(handler, 0, 62, 17));
		this.addSlotToContainer(new SlotItemHandler(handler, 1, 98, 17));
		this.addSlotToContainer(new SlotItemHandler(handler, 2, 62, 53));
		// The player's inventory slots
		int xPos = 8; // The x position of the top left player inventory
						// slot on our texture
		int yPos = 84; // The y position of the top left player inventory
						// slot on our texture

		// Player slots
		for (int y = 0; y < 3; ++y) {
			for (int x = 0; x < 9; ++x) {
				this.addSlotToContainer(new Slot(playerInv, x + y * 9 + 9, xPos + x * 18, yPos + y * 18));
			}
		}

		for (int x = 0; x < 9; ++x) {
			this.addSlotToContainer(new Slot(playerInv, x, xPos + x * 18, yPos + 58));
		}
		// TODO Auto-generated constructor stub
	}

	@Override
	public boolean canInteractWith(EntityPlayer player) {
		// TODO Auto-generated method stub
		return true;
	}

}

package com.teamapplejuice.gui;

import com.teamapplejuice.stats.Stats;
import com.teamapplejuice.tileentity.TileEntityOrbMaker;

import net.minecraft.entity.player.EntityPlayer;
import net.minecraft.util.math.BlockPos;
import net.minecraft.world.World;
import net.minecraftforge.fml.common.network.IGuiHandler;

public class GuiHandler implements IGuiHandler
{
	public static final int ORB_MAKER=112;
	@Override
	public Object getServerGuiElement(int ID, EntityPlayer player, World world, int x, int y, int z) {
		// TODO Auto-generated method stub
		if(ID==ORB_MAKER)
			return new ContainerOrbMaker((TileEntityOrbMaker) world.getTileEntity(new BlockPos(x, y, z)), player.inventory);
		return null;
	}

	@Override
	public Object getClientGuiElement(int ID, EntityPlayer player, World world, int x, int y, int z) {
		// TODO Auto-generated method stub
		if(ID==ORB_MAKER)
			return new GUIOrbMaker(player.inventory, (TileEntityOrbMaker) world.getTileEntity(new BlockPos(x, y, z)));
		return null;
	}
}

 

Don't implement ITileEntityProvider instead override hasTileEntity(IBlockState) and createTileEntity(World, IBlockState).

 

Post your TileEntity.