WHY

---- Minecraft Crash Report ----
// I blame Dinnerbone.

Time: 07.07.20 15:13
Description: Exception in server tick loop

cpw.mods.fml.common.LoaderException: java.lang.NoClassDefFoundError: net/minecraft/client/multiplayer/WorldClient
    at cpw.mods.fml.common.LoadController.transition(LoadController.java:163)
    at cpw.mods.fml.common.Loader.initializeMods(Loader.java:739)
    at cpw.mods.fml.server.FMLServerHandler.finishServerLoading(FMLServerHandler.java:97)
    at cpw.mods.fml.common.FMLCommonHandler.onServerStarted(FMLCommonHandler.java:319)
    at net.minecraft.server.dedicated.DedicatedServer.func_71197_b(DedicatedServer.java:210)
    at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:387)
    at net.minecraft.server.MinecraftServer$2.run(MinecraftServer.java:685)
Caused by: java.lang.NoClassDefFoundError: net/minecraft/client/multiplayer/WorldClient
    at DamageIndicatorsMod.server.DIProxy.register(DIProxy.java:11)
    at DamageIndicatorsMod.DIMod.load(DIMod.java:64)
    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:532)
    at sun.reflect.GeneratedMethodAccessor4.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:212)
    at cpw.mods.fml.common.LoadController.propogateStateMessage(LoadController.java:190)
    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:119)
    at cpw.mods.fml.common.Loader.initializeMods(Loader.java:737)
    ... 5 more
Caused by: java.lang.ClassNotFoundException: net.minecraft.client.multiplayer.WorldClient
    at net.minecraft.launchwrapper.LaunchClassLoader.findClass(LaunchClassLoader.java:191)
    at java.lang.ClassLoader.loadClass(Unknown Source)
    at java.lang.ClassLoader.loadClass(Unknown Source)
    ... 33 more
Caused by: java.lang.RuntimeException: Attempted to load class bjf for invalid side SERVER
    at cpw.mods.fml.common.asm.transformers.SideTransformer.transform(SideTransformer.java:50)
    at net.minecraft.launchwrapper.LaunchClassLoader.runTransformers(LaunchClassLoader.java:279)
    at net.minecraft.launchwrapper.LaunchClassLoader.findClass(LaunchClassLoader.java:176)
    ... 35 more

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

-- System Details --
Details:
    Minecraft Version: 1.7.10
    Operating System: Windows 10 (x86) version 10.0
    Java Version: 1.8.0_251, Oracle Corporation
    Java VM Version: Java HotSpot(TM) Client VM (mixed mode), Oracle Corporation
    Memory: 836459288 bytes (797 MB) / 1037959168 bytes (989 MB) up to 1037959168 bytes (989 MB)
    JVM Flags: 2 total; -Xms1G -Xmx1G
    AABB Pool Size: 0 (0 bytes; 0 MB) allocated, 0 (0 bytes; 0 MB) used
    IntCache: cache: 0, tcache: 0, allocated: 0, tallocated: 0
    FML: MCP v9.05 FML v7.10.99.99 Minecraft Forge 10.13.4.1614 28 mods loaded, 28 mods active
    States: 'U' = Unloaded 'L' = Loaded 'C' = Constructed 'H' = Pre-initialized 'I' = Initialized 'J' = Post-initialized 'A' = Available 'D' = Disabled 'E' = Errored
    UCHI    mcp{9.05} [Minecraft Coder Pack] (minecraft.jar) 
    UCHI    FML{7.10.99.99} [Forge Mod Loader] (forge-1.7.10-10.13.4.1614-1.7.10-universal.jar) 
    UCHI    Forge{10.13.4.1614} [Minecraft Forge] (forge-1.7.10-10.13.4.1614-1.7.10-universal.jar) 
    UCHI    AM2-Preloader{0.0.3} [AMCore] (minecraft.jar) 
    UCHI    CodeChickenCore{1.0.7.47} [CodeChicken Core] (minecraft.jar) 
    UCHI    ivtoolkit{1.2.1} [IvToolkit] (minecraft.jar) 
    UCHI    NotEnoughItems{1.0.5.120} [Not Enough Items] (NotEnoughItems-1.7.10-1.0.5.120-universal.jar) 
    UCHI    FastCraft{1.25} [FastCraft] (fastcraft-1.25.jar) 
    UCHI    zeldaswordskills{1.7.10-2.5.1} [Zelda Sword Skills] (1.7.10-zeldaswordskills-2.5.1.jar) 
    UCHI    AnimationAPI{1.2.4} [AnimationAPI] (AnimationAPI-1.7.10-1.2.4.jar) 
    UCHI    arsmagica2{1.4.0.009} [Ars Magica 2] (1.7.10_AM2-1.4.0.009.jar) 
    UCHI    Aquaculture{1.2.3} [Aquaculture] (14171662183_Aquaculture-Mod-1.7.10.jar) 
    UCHI    simplecore{1.1.1.3} [SimpleCore API] (SimpleCore-API-1.7.10.jar) 
    UCHI    netherrocks{1.3.0} [Netherrocks] ([1.7.10]+Netherrocks+v1.3.0.jar) 
    UCHI    simpleores{1.6.0} [SimpleOres 2] ([1.7.10]+SimpleOres+2+v1.6.0.jar) 
    UCHI    fusion{1.6.1.1} [Fusion] (fusion-1.7.10-1.6.1.1.jar) 
    UCHI    aesthetics{1.1.0} [Aesthetics] ([1.7.10]+Aesthetics+v1.1.0.jar) 
    UCHE    DamageIndicatorsMod{3.3.2} [Damage Indicators] ([1.7.10]DamageIndicatorsMod-3.3.2.jar) 
    UCHI    animalbikes{1.7.10} [Animal Bikes] (AnimalBikes_1.7.10.jar) 
    UCHI    BiomesOPlenty{2.0.2} [Biomes O' Plenty] (Biomes O Plenty Mod v1.7.10.jar) 
    UCHI    iChunUtil{4.0.0} [iChunUtil] (iChunUtil-4.0.0.jar) 
    UCHI    IronChest{6.0.41.729} [Iron Chest] (Iron-Chests-Mod-1.7.10.jar) 
    UCHI    MobAmputation{4.0.1} [MobAmputation] (MobAmputation-4.0.1.jar) 
    UCHI    MobDismemberment{4.0.0} [MobDismemberment] (MobDismemberment-4.0.0.jar) 
    UCHI    notenoughIDs{1.4.3.4} [NotEnoughIDs] (NotEnoughIDs-1.4.3.4.jar) 
    UCHI    reccomplex{0.9.7.1.1} [Recurrent Complex] (RecurrentComplex-0.9.7.1.1.jar) 
    UCHI    SpecialMobs{3.2.2} [Special Mobs] (SpecialMobs-1.7.10-3.2.2.jar) 
    UCHI    zssaddon{1.7.10-alpha-0.0.5-2} [Zelda Sword Skills - Addon] (zeldaswordskillsaddon-v0.0.6.jar) 
    Profiler Position: N/A (disabled)
    Is Modded: Definitely; Server brand changed to 'fml,forge'
    Type: Dedicated Server (map_server.txt)