TS1 - GC issue

net.minecraft.util.ReportedException: Exception getting block type in world
        at net.minecraft.world.World.func_147439_a(World.java:354) ~[ahb.class:?]
        at micdoodle8.mods.galacticraft.core.event.EventHandlerGC.checkBlock(EventHandlerGC.java:417) ~[EventHandlerGC.class:?]
        at micdoodle8.mods.galacticraft.core.event.EventHandlerGC.doPopulate(EventHandlerGC.java:382) ~[EventHandlerGC.class:?]
        at micdoodle8.mods.galacticraft.core.event.EventHandlerGC.populate(EventHandlerGC.java:334) ~[EventHandlerGC.class:?]
        at cpw.mods.fml.common.eventhandler.ASMEventHandler_276_EventHandlerGC_populate_Post.invoke(.dynamic) ~[?:?]
        at cpw.mods.fml.common.eventhandler.ASMEventHandler.invoke(ASMEventHandler.java:54) ~[ASMEventHandler.class:?]
        at cpw.mods.fml.common.eventhandler.EventBus.post(EventBus.java:138) [EventBus.class:?]
        at net.minecraft.world.gen.ChunkProviderGenerate.func_73153_a(ChunkProviderGenerate.java:448) [aqz.class:?]