[20:58:16] [Client thread/ERROR] [FML]: An exception occurred while loading config file GregTech.lang. This file will be renamed to GregTech.lang_20150424_205816.errored and a new config file will be generated.
java.lang.StringIndexOutOfBoundsException: String index out of range: -1
	at java.lang.String.substring(Unknown Source)
	at net.minecraftforge.common.config.Configuration.load(Configuration.java:937)
	at net.minecraftforge.common.config.Configuration.<init>(Configuration.java:109)
	at net.minecraftforge.common.config.Configuration.<init>(Configuration.java:87)
	at gregapi.GT_API.onPreLoad(GT_API.java:270)
	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 cpw.mods.fml.common.FMLModContainer.handleModStateEvent(FMLModContainer.java:513)
	at sun.reflect.GeneratedMethodAccessor5.invoke(Unknown Source)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
	at java.lang.reflect.Method.invoke(Unknown Source)
	at com.google.common.eventbus.EventSubscriber.handleEvent(EventSubscriber.java:74)
	at com.google.common.eventbus.SynchronizedEventSubscriber.handleEvent(SynchronizedEventSubscriber.java:47)
	at com.google.common.eventbus.EventBus.dispatch(EventBus.java:322)
	at com.google.common.eventbus.EventBus.dispatchQueuedEvents(EventBus.java:304)
	at com.google.common.eventbus.EventBus.post(EventBus.java:275)
	at cpw.mods.fml.common.LoadController.sendEventToModContainer(LoadController.java:208)
	at cpw.mods.fml.common.LoadController.propogateStateMessage(LoadController.java:187)
	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 com.google.common.eventbus.EventSubscriber.handleEvent(EventSubscriber.java:74)
	at com.google.common.eventbus.SynchronizedEventSubscriber.handleEvent(SynchronizedEventSubscriber.java:47)
	at com.google.common.eventbus.EventBus.dispatch(EventBus.java:322)
	at com.google.common.eventbus.EventBus.dispatchQueuedEvents(EventBus.java:304)
	at com.google.common.eventbus.EventBus.post(EventBus.java:275)
	at cpw.mods.fml.common.LoadController.distributeStateMessage(LoadController.java:118)
	at cpw.mods.fml.common.Loader.preinitializeMods(Loader.java:513)
	at cpw.mods.fml.client.FMLClientHandler.beginMinecraftLoading(FMLClientHandler.java:239)
	at net.minecraft.client.Minecraft.func_71384_a(Minecraft.java:480)
	at net.minecraft.client.Minecraft.func_99999_d(Minecraft.java:867)
	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)