Minecraft 1.12.2
Erebus 1.0.19

Player was fighting a Crushroom, this caused a server crash. Replicated twice more.

Partial log below:

---- Minecraft Crash Report ----

WARNING: coremods are present:
CTMCorePlugin (CTM-MC1.12-0.2.3.12.jar)
LoadingPlugin (Quark-r1.4-121.jar)
AstralCore (astralsorcery-1.12.2-1.8.4.jar)
IELoadingPlugin (ImmersiveEngineering-0.12-76-core.jar)
AdvancedRocketryPlugin (AdvancedRocketry-1.12.2-1.2.6-49.jar)
Plugin (NotEnoughIDs-1.5.4.2.jar)
Wizardry Plugin (wizardry-0.7.2.jar)
CoreMod (Aroma1997Core-1.12.2-1.3.0.2.jar)
Inventory Tweaks Coremod (InventoryTweaks-1.64-dev.jar)
ForgelinPlugin (Forgelin-1.6.0.jar)
Do not report to Forge! Remove FoamFixAPI (or replace with FoamFixAPI-Lawful) and try again. (FoamFix-1.12.2-0.8.4-Anarchy.jar)
TransformerLoader (OpenComputers-MC1.12.1-1.7.1.43.jar)
LibrarianLib Plugin (librarianlib-1.12.2-4.4.jar)
Contact their authors BEFORE contacting forge

// Ooh. Shiny.

Time: 3/6/18 1:14 PM
Description: Ticking entity

java.lang.NoSuchMethodError: net.minecraft.entity.player.InventoryPlayer.func_70440_f(I)Lnet/minecraft/item/ItemStack;
at erebus.entity.EntitySporeBall.func_70184_a(EntitySporeBall.java:71)
at net.minecraft.entity.projectile.EntityThrowable.func_70071_h_(EntityThrowable.java:249)
at erebus.entity.EntitySporeBall.func_70071_h_(EntitySporeBall.java:42)
at net.minecraft.world.World.func_72866_a(World.java:1990)
at net.minecraft.world.WorldServer.func_72866_a(WorldServer.java:831)
at net.minecraft.world.World.func_72870_g(World.java:1952)
at net.minecraft.world.World.func_72939_s(World.java:1756)
at net.minecraft.world.WorldServer.func_72939_s(WorldServer.java:612)
at net.minecraft.server.MinecraftServer.func_71190_q(MinecraftServer.java:765)
at net.minecraft.server.dedicated.DedicatedServer.func_71190_q(DedicatedServer.java:396)
at net.minecraft.server.MinecraftServer.func_71217_p(MinecraftServer.java:666)
at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:524)
at java.lang.Thread.run(Unknown Source)

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

-- Head --
Thread: Server thread
Stacktrace:
at erebus.entity.EntitySporeBall.func_70184_a(EntitySporeBall.java:71)
at net.minecraft.entity.projectile.EntityThrowable.func_70071_h_(EntityThrowable.java:249)
at erebus.entity.EntitySporeBall.func_70071_h_(EntitySporeBall.java:42)
at net.minecraft.world.World.func_72866_a(World.java:1990)
at net.minecraft.world.WorldServer.func_72866_a(WorldServer.java:831)
at net.minecraft.world.World.func_72870_g(World.java:1952)

-- Entity being ticked --
Details:
Entity Type: erebus:erebus.spore_ball (erebus.entity.EntitySporeBall)
Entity ID: 20739
Entity Name: entity.erebus.spore_ball.name
Entity's Exact location: -328.10, 57.02, 39.06
Entity's Block location: World: (-329,57,39), Chunk: (at 7,3,7 in -21,2; contains blocks -336,0,32 to -321,255,47), Region: (-1,0; contains chunks -32,0 to -1,31, blocks -512,0,0 to -1,255,511)
Entity's Momentum: -0.39, -0.47, -0.58
Entity's Passengers: []
Entity's Vehicle: ERROR NullPointerException: null
Stacktrace:
at net.minecraft.world.World.func_72939_s(World.java:1756)
at net.minecraft.world.WorldServer.func_72939_s(WorldServer.java:612)

-- Affected level --
Details:
Level name: world
All players: 1 total; [EntityPlayerMP[''/20736, l='world', x=-328.01, y=56.00, z=39.32]]
Chunk stats: ServerChunkCache: 297 Drop: 0
Level seed: -4525594095367697830
Level generator: ID 00 - default, ver 1. Features enabled: false
Level generator options:
Level spawn location: World: (0,0,0), Chunk: (at 0,0,0 in 0,0; contains blocks 0,0,0 to 15,255,15), Region: (0,0; contains chunks 0,0 to 31,31, blocks 0,0,0 to 511,255,511)
Level time: 0 game time, 0 day time
Level dimension: 0
Level storage version: 0x00000 - Unknown?
Level weather: Rain time: 0 (now: false), thunder time: 0 (now: false)
Level game mode: Game mode: survival (ID 0). Hardcore: false. Cheats: false
Stacktrace:
at net.minecraft.server.MinecraftServer.func_71190_q(MinecraftServer.java:765)
at net.minecraft.server.dedicated.DedicatedServer.func_71190_q(DedicatedServer.java:396)
at net.minecraft.server.MinecraftServer.func_71217_p(MinecraftServer.java:666)
at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:524)
at java.lang.Thread.run(Unknown Source)

Will be fixed in the next release, was a client method being used where it shouldn't - doh!
New fix release will be up in a couple of days, closing due to it fixed in dev now.
Thanks for finding it out and reporting :)