We all knew that Soggy was gonna break your addon.
Here's the relevant part of log.

[09:55:13] [Server thread/ERROR] [FML]: Encountered an exception while constructing entity 'lilcritters:treesquirrel' java.lang.reflect.InvocationTargetException: null at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method) ~[?:1.8.0_191] at sun.reflect.NativeConstructorAccessorImpl.newInstance(Unknown Source) ~[?:1.8.0_191] at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(Unknown Source) ~[?:1.8.0_191] at java.lang.reflect.Constructor.newInstance(Unknown Source) ~[?:1.8.0_191] at net.minecraftforge.fml.common.registry.EntityEntryBuilder$ConstructorFactory.apply(EntityEntryBuilder.java:304) [EntityEntryBuilder$ConstructorFactory.class:?] at net.minecraftforge.fml.common.registry.EntityEntryBuilder$ConstructorFactory.apply(EntityEntryBuilder.java:290) [EntityEntryBuilder$ConstructorFactory.class:?] at net.minecraftforge.fml.common.registry.EntityEntry.newInstance(EntityEntry.java:68) [EntityEntry.class:?] at net.minecraft.world.biome.Biome$SpawnListEntry.newInstance(Biome.java:655) [anh$c.class:?] at sun.reflect.GeneratedMethodAccessor32.invoke(Unknown Source) ~[?:?] at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source) ~[?:1.8.0_191] at java.lang.reflect.Method.invoke(Unknown Source) ~[?:1.8.0_191] at net.optifine.reflect.Reflector.call(Reflector.java:961) [Reflector.class:?] at net.minecraft.world.WorldEntitySpawner.func_77192_a(WorldEntitySpawner.java:214) [anb.class:?] at net.minecraft.world.WorldServer.func_72835_b(WorldServer.java:203) [oo.class:?] at net.optifine.override.WorldServerOF.func_72835_b(WorldServerOF.java:39) [WorldServerOF.class:?] at net.minecraft.server.MinecraftServer.func_71190_q(MinecraftServer.java:756) [MinecraftServer.class:?] at net.minecraft.server.MinecraftServer.func_71217_p(MinecraftServer.java:668) [MinecraftServer.class:?] at net.minecraft.server.integrated.IntegratedServer.func_71217_p(IntegratedServer.java:252) [chd.class:?] at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:526) [MinecraftServer.class:?] at java.lang.Thread.run(Unknown Source) [?:1.8.0_191] Caused by: java.lang.NoSuchFieldError: aiWander at com.github.mnesikos.lilcritters.entity.EntityBaseAvoidWater.func_184651_r(EntityBaseAvoidWater.java:15) ~[EntityBaseAvoidWater.class:?] at com.github.mnesikos.lilcritters.entity.EntityTreeSquirrel.func_184651_r(EntityTreeSquirrel.java:70) ~[EntityTreeSquirrel.class:?] at net.minecraft.entity.EntityLiving.<init>(EntityLiving.java:134) ~[vq.class:?] at net.minecraft.entity.EntityCreature.<init>(SourceFile:21) ~[vx.class:?] at net.minecraft.entity.EntityAgeable.<init>(EntityAgeable.java:27) ~[vd.class:?] at net.minecraft.entity.passive.EntityAnimal.<init>(SourceFile:30) ~[zv.class:?] at net.minecraft.entity.passive.EntityTameable.<init>(SourceFile:31) ~[wb.class:?] at org.zawamod.entity.base.ZAWABaseLand.<init>(ZAWABaseLand.java:148) ~[ZAWABaseLand.class:?] at com.github.mnesikos.lilcritters.entity.EntityBase.<init>(EntityBase.java:20) ~[EntityBase.class:?] at com.github.mnesikos.lilcritters.entity.EntityBaseAvoidWater.<init>(EntityBaseAvoidWater.java:9) ~[EntityBaseAvoidWater.class:?] at com.github.mnesikos.lilcritters.entity.EntityTreeSquirrel.<init>(EntityTreeSquirrel.java:53) ~[EntityTreeSquirrel.class:?] ... 20 more [09:55:13] [Server thread/ERROR] [minecraft/MinecraftServer]: Encountered an unexpected exception net.minecraft.util.ReportedException: Exception ticking world at net.minecraft.server.MinecraftServer.func_71190_q(MinecraftServer.java:762) ~[MinecraftServer.class:?] at net.minecraft.server.MinecraftServer.func_71217_p(MinecraftServer.java:668) ~[MinecraftServer.class:?] at net.minecraft.server.integrated.IntegratedServer.func_71217_p(IntegratedServer.java:252) ~[chd.class:?] at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:526) [MinecraftServer.class:?] at java.lang.Thread.run(Unknown Source) [?:1.8.0_191] Caused by: java.lang.NullPointerException at net.minecraft.world.WorldEntitySpawner.func_77192_a(WorldEntitySpawner.java:229) ~[anb.class:?] at net.minecraft.world.WorldServer.func_72835_b(WorldServer.java:203) ~[oo.class:?] at net.optifine.override.WorldServerOF.func_72835_b(WorldServerOF.java:39) ~[WorldServerOF.class:?] at net.minecraft.server.MinecraftServer.func_71190_q(MinecraftServer.java:756) ~[MinecraftServer.class:?]

Fixed! (Hopefully lol)