Need help tracking Entity through TileEntity[1.8]

With my TileEntity, i wanna change the y positon of all of the entities on it to a dynamicly set position. Now i struggle in the way i track this entity. I set it in the blockcode like this:

@Override
public void onEntityCollidedWithBlock(World worldIn, BlockPos pos, Entity entityIn) {
	if (worldIn.getTileEntity(pos) != null && worldIn.getTileEntity(pos) instanceof TileEntityTarmac) {
		TileEntityTarmac t = (TileEntityTarmac) worldIn.getTileEntity(pos);
		t.entities.add(entityIn.getEntityId());
	} else {
	}
}

Now i try this in my tileentity:

@Override
public void update() {
	if (!this.hasWorldObj())
		return;
	if (!entities.isEmpty()) {
		Entity e = null;
		for (int i = 0; i < entities.size() - 1; i++) {
			e = worldObj.getEntityByID(i);
			if (e != null && !e.isDead && heightfile != null) {
				{
					e.setPosition(e.posX, this.getPosForEntity(e, heightfile), e.posZ);
				}
				if (!worldObj.isRemote)
					if (e.posX < pos.getX() || e.posZ < pos.getZ() || e.isDead || e.isCollided) {
						entities.remove(i);
					}
			}
		}
	}
}

Now what is happening is really strange. It just crashes, saying something about lastTwoElementsOfStackTrace but not where the error is. What am i doing wrong in my method?