Nucleus world save issue

---- Minecraft Crash Report ----

WARNING: coremods are present:
  SpongeCoremod (spongeforge-1.12-2443-7.0.0-BETA-2498.jar)
  BetterSprintingCore (BetterSprinting  MC-1.12  v2.0.2.jar)
Contact their authors BEFORE contacting forge

// Surprise! Haha. Well, this is awkward.

Time: 9/7/17 8:40 PM
Description: Exception in server tick loop

java.lang.ClassCastException: net.minecraft.world.gen.ChunkProviderServer cannot be cast to org.spongepowered.common.interfaces.world.gen.IMixinChunkProviderServer
	at net.minecraft.world.WorldServer.setActiveConfig(WorldServer.java:1813)
	at org.spongepowered.common.util.SpongeHooks.getActiveConfig(SpongeHooks.java:450)
	at org.spongepowered.common.util.SpongeHooks.getActiveConfig(SpongeHooks.java:457)
	at net.minecraft.world.WorldServer.handler$onConstruct$zkh000(WorldServer.java:1704)
	at net.minecraft.world.WorldServer.<init>(WorldServer.java:124)
	at org.spongepowered.common.world.WorldManager.createWorldFromProperties(WorldManager.java:778)
	at org.spongepowered.common.world.WorldManager.loadAllWorlds(WorldManager.java:749)
	at net.minecraft.server.MinecraftServer.func_71247_a(MinecraftServer.java:3548)
	at net.minecraft.server.dedicated.DedicatedServer.func_71197_b(DedicatedServer.java:267)
	at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:483)
	at java.lang.Thread.run(Thread.java:745)


A detailed walkthrough of the error, its code path and all known details is as follows:
---------------------------------------------------------------------------------------

-- Head --
Thread: Server thread
Stacktrace:
	at net.minecraft.world.WorldServer.setActiveConfig(WorldServer.java:1813)
	at org.spongepowered.common.util.SpongeHooks.getActiveConfig(SpongeHooks.java:450)
	at org.spongepowered.common.util.SpongeHooks.getActiveConfig(SpongeHooks.java:457)
	at net.minecraft.world.WorldServer.handler$onConstruct$zkh000(WorldServer.java:1704)
	at net.minecraft.world.WorldServer.<init>(WorldServer.java:124)
	at org.spongepowered.common.world.WorldManager.createWorldFromProperties(WorldManager.java:778)

-- Sponge CauseTracker --
Details:
	Cause Stack: [Empty stack]
Stacktrace:
	at net.minecraft.server.MinecraftServer.handler$onCrashReport$zia000(MinecraftServer.java:3998)
	at net.minecraft.server.MinecraftServer.func_71230_b(MinecraftServer.java:883)
	at net.minecraft.server.dedicated.DedicatedServer.func_71230_b(DedicatedServer.java:365)
	at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:555)
	at java.lang.Thread.run(Thread.java:745)

-- System Details --
Details:
	Minecraft Version: 1.12
	Operating System: Linux (amd64) version 3.10.0-514.2.2.el7.x86_64
	Java Version: 1.8.0_102, Oracle Corporation
	Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Oracle Corporation
	Memory: 108762632 bytes (103 MB) / 472014848 bytes (450 MB) up to 8382709760 bytes (7994 MB)
	JVM Flags: 10 total; -Xms32M -Xmx8270M -XX:OnOutOfMemoryError=curl https://api.creeper.host/callbacks/minecraft/outofmemory.php?instance=mc-59a70dc423461 -k -XX:OnError=curl http://api.creeper.host/callbacks/minecraft/crash.php?instance=mc-59a70dc423461 -k -XX:+UseParNewGC -XX:+CMSIncrementalPacing -XX:+CMSClassUnloadingEnabled -XX:ParallelGCThreads=8 -XX:MinHeapFreeRatio=5 -XX:MaxHeapFreeRatio=10
	IntCache: cache: 0, tcache: 0, allocated: 0, tallocated: 0
	FML: MCP 9.40 Powered by Forge 14.21.1.2443 26 mods loaded, 26 mods active
	States: 'U' = Unloaded 'L' = Loaded 'C' = Constructed 'H' = Pre-initialized 'I' = Initialized 'J' = Post-initialized 'A' = Available 'D' = Disabled 'E' = Errored
	UCHIJAA	minecraft{1.12} [Minecraft] (minecraft.jar)
	UCHIJAA	mcp{9.19} [Minecraft Coder Pack] (minecraft.jar)
	UCHIJAA	FML{8.0.99.99} [Forge Mod Loader] (forge-1.12-14.21.1.2443-universal.jar)
	UCHIJAA	forge{14.21.1.2443} [Minecraft Forge] (forge-1.12-14.21.1.2443-universal.jar)
	UCHIJAA	spongeapi{7.0.0-SNAPSHOT-4beb0b2} [SpongeAPI] (spongeforge-1.12-2443-7.0.0-BETA-2498.jar)
	UCHIJAA	sponge{1.12-2443-7.0.0-BETA-2498} [SpongeForge] (spongeforge-1.12-2443-7.0.0-BETA-2498.jar)
	UCHIJAA	nucleus-mixin{0.25.2-5.1} [Nucleus Mixins] (NucleusMixins-0.25.2-5.1.jar)
	UCHIJAA	bettersprinting{2.0.2} [Better Sprinting] (BetterSprinting  MC-1.12  v2.0.2.jar)
	UCHIJAA	economylite{2.12.0} [EconomyLite] (EconomyLite-5.0.0-2.12.0.jar)
	UCHIJAA	enjin-minecraft-plugin{3.3.3-sponge} [Enjin Minecraft Plugin] (EMPSponge.jar)
	UCHIJAA	griefprevention{4.2.0} [GriefPrevention] (griefprevention-1.12.1-4.2.0.393.jar)
	UCHIJAA	holograms{2.2} [Holograms] (holograms-2.2.jar)
	UCHIJAA	luckperms{3.3.19} [LuckPerms] (LuckPerms-Sponge-3.3.19.jar)
	UCHIJAA	minereset{1.0.7} [MineReset] (MineReset-1.0.7.jar)
	UCHIJAA	mmcrules{1.1} [MMCRules] (MMCRules-1.1-API-5.0.0.jar)
	UCHIJAA	morpheus{1.12-3.3.2} [Morpheus] (Morpheus-1.12-3.3.2.jar)
	UCHIJAA	nucleus{1.1.1-S7.0} [Nucleus] (Nucleus-1.1.1-MC1.12.1-S7.0-plugin.jar)
	UCHIJAA	pjc{0.2.0} [ProjectCore for SpongeAPI 7.x] (projectcore-7.0.0-0.2.0.jar)
	UCHIJAA	pjp{0.13.8} [ProjectPortals for SpongeAPI 5.x] (projectportals-5.2.0-0.13.8.jar)
	UCHIJAA	pvptoggle{1.2.0} [PvpToggle] (PvPToggle-1.2.0.jar)
	UCHIJAA	spongychest{0.4.8} [SpongyChest] (SpongyChest-1.10.2-0.4.8-universal.jar)
	UCHIJAA	tabmanager{1.0.4} [TabManager] (TabManager-1.0.4.jar)
	UCHIJAA	tmotd{1.0} [TitleMOTD] (TitleMOTD.-.1.0.jar)
	UCHIJAA	virtualtool{3.0} [VirtualTool] (VirtualTool-1.10.2-3.0.jar)
	UCHIJAA	walletdrop{0.3.0} [WalletDrop for SpongeAPI 7.x] (walletdrop-7.0.0-0.3.0.jar)
	UCHIJAA	winterwonderland{1.3.0} [Winter Wonderland] (WinterWonderland-5.1.0-1.3.0.jar)
	Loaded coremods (and transformers):
SpongeCoremod (spongeforge-1.12-2443-7.0.0-BETA-2498.jar)
  org.spongepowered.common.launch.transformer.SpongeSuperclassTransformer
BetterSprintingCore (BetterSprinting  MC-1.12  v2.0.2.jar)
  chylex.bettersprinting.system.core.TransformerEntityPlayerSP
	Profiler Position: N/A (disabled)
	Player Count: 0 / 100; []
	Is Modded: Definitely; Server brand changed to 'fml,forge,sponge'
	Type: Dedicated Server (map_server.txt)