V10verlap 4.0 on single player triggering a bug

[V10lator]

This happens randomly when jumping from / climbing to another world in V10verlap 4.0 on single player:

java.util.concurrent.ExecutionException: java.lang.RuntimeException: Cannot Hotload Dim: Overworld is not Loaded!
    at java.util.concurrent.FutureTask.report(FutureTask.java:122)
    at java.util.concurrent.FutureTask.get(FutureTask.java:192)
    at net.minecraft.util.Util.runTask(SourceFile:531)
    at net.minecraft.client.Minecraft.runGameLoop(Minecraft.java:1086)
    at net.minecraft.client.Minecraft.run(Minecraft.java:4437)
    at net.minecraft.client.main.Main.main(SourceFile:123)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at net.minecraft.launchwrapper.Launch.launch(Launch.java:135)
    at net.minecraft.launchwrapper.Launch.main(Launch.java:28)
Caused by: java.lang.RuntimeException: Cannot Hotload Dim: Overworld is not Loaded!
    at net.minecraftforge.common.DimensionManager.initDimension(DimensionManager.java:232)
    at net.minecraft.server.MinecraftServer.getWorld(MinecraftServer.java:832)
    at com.mamiyaotaru.voxelmap.b.b.<init>(Unknown Source)
    at com.mamiyaotaru.voxelmap.b.p.do(Unknown Source)
    at com.mamiyaotaru.voxelmap.util.K.do(Unknown Source)
    at com.mamiyaotaru.voxelmap.util.K.markBlockRangeForRenderUpdate(Unknown Source)
    at net.minecraft.world.World.markBlockRangeForRenderUpdate(World.java:472)
    at net.minecraft.client.network.NetHandlerPlayClient.handleChunkData(NetHandlerPlayClient.java:746)
    at net.minecraft.network.play.server.SPacketChunkData.processPacket(SourceFile:96)
    at net.minecraft.network.play.server.SPacketChunkData.processPacket(SourceFile:18)
    at net.minecraft.network.PacketThreadUtil$1.run(SourceFile:13)
    at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
    at java.util.concurrent.FutureTask.run(FutureTask.java:266)
    at net.minecraft.util.Util.runTask(SourceFile:529)
    ... 9 more