java.lang.NullPointerException: Ticking screen
at net.minecraft.client.gui.inventory.GuiContainer.func_73876_c(GuiContainer.java:698)
at com.dynious.refinedrelocation.client.gui.GuiRefinedRelocationContainer.func_73876_c(GuiRefinedRelocationContainer.java:114)
at net.minecraft.client.Minecraft.func_71407_l(Minecraft.java:1661)
at net.minecraft.client.Minecraft.func_71411_J(Minecraft.java:973)
at net.minecraft.client.Minecraft.func_99999_d(Minecraft.java:898)
at net.minecraft.client.main.Main.main(SourceFile:148)
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)
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 org.multimc.onesix.OneSixLauncher.launchWithMainClass(OneSixLauncher.java:286)
at org.multimc.onesix.OneSixLauncher.launch(OneSixLauncher.java:376)
at org.multimc.EntryPoint.listen(EntryPoint.java:170)
at org.multimc.EntryPoint.main(EntryPoint.java:54)

Wasn't reproduceable and the only thing that could be null in the function was mc or thePlayer, so blaming general Minecraft weirdness and closing this for now.