java.lang.IllegalArgumentException: Cannot get property null as it does not exist in BlockStateContainer{block=basemetals:gold_slab, properties=[half]}
    at net.minecraft.block.state.BlockStateContainer$StateImplementation.func_177229_b(BlockStateContainer.java:201)
    at net.minecraft.item.ItemSlab.func_180614_a(ItemSlab.java:57)
    at com.mcmoddev.lib.item.ItemMMDSlab.func_180614_a(ItemMMDSlab.java:102)
    at net.minecraft.item.ItemStack.func_179546_a(ItemStack.java:187)
    at net.minecraft.client.multiplayer.PlayerControllerMP.func_187099_a(PlayerControllerMP.java:467)
    at net.minecraft.client.Minecraft.func_147121_ag(Minecraft.java:1577)
    at net.minecraft.client.Minecraft.func_184117_aA(Minecraft.java:2252)
    at net.minecraft.client.Minecraft.func_184118_az(Minecraft.java:2018)
    at net.minecraft.client.Minecraft.func_71407_l(Minecraft.java:1806)
    at net.minecraft.client.Minecraft.func_71411_J(Minecraft.java:1096)
    at net.minecraft.client.Minecraft.func_99999_d(Minecraft.java:397)
    at net.minecraft.client.main.Main.main(SourceFile:123)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
    at java.lang.reflect.Method.invoke(Unknown Source)
    at net.minecraft.launchwrapper.Launch.launch(Launch.java:135)
    at net.minecraft.launchwrapper.Launch.main(Launch.java:28)