Crash Loading World

Game crashes on world load. Attached is the relevant crash report.
Think there's anyway to get the map back? I put some time into it and don't want to see my work go to waste.

---- Minecraft Crash Report ----
// Don't be sad. I'll do better next time, I promise!

Time: 3/26/18 11:59 PM
Description: Ticking entity

java.lang.ClassCastException: afn cannot be cast to afj
	at adb.a(SourceFile:41)
	at acz.a(SourceFile:22)
	at adl.a(SourceFile:94)
	at abw.cL(SourceFile:644)
	at abv.l(SourceFile:1895)
	at abw.l(SourceFile:504)
	at ajs.l(SourceFile:33)
	at aki.l(SourceFile:257)
	at abv.S_(SourceFile:1750)
	at abw.S_(SourceFile:284)
	at ajs.S_(SourceFile:38)
	at aki.S_(SourceFile:232)
	at ajg.S_(SourceFile:252)
	at aug.a(SourceFile:1617)
	at se.a(SourceFile:705)
	at aug.h(SourceFile:1593)
	at aug.p_(SourceFile:1475)
	at se.p_(SourceFile:538)
	at net.minecraft.server.MinecraftServer.w(SourceFile:702)
	at net.minecraft.server.MinecraftServer.v(SourceFile:627)
	at czd.v(SourceFile:155)
	at net.minecraft.server.MinecraftServer.run(SourceFile:532)
	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 adb.a(SourceFile:41)
	at acz.a(SourceFile:22)
	at adl.a(SourceFile:94)
	at abw.cL(SourceFile:644)
	at abv.l(SourceFile:1895)
	at abw.l(SourceFile:504)
	at ajs.l(SourceFile:33)
	at aki.l(SourceFile:257)
	at abv.S_(SourceFile:1750)
	at abw.S_(SourceFile:284)
	at ajs.S_(SourceFile:38)
	at aki.S_(SourceFile:232)
	at ajg.S_(SourceFile:252)
	at aug.a(SourceFile:1617)
	at se.a(SourceFile:705)
	at aug.h(SourceFile:1593)

-- Entity being ticked --
Details:
	Entity Type: minecraft:drowned (ajg)
	Entity ID: 354
	Entity Name: Drowned
	Entity's Exact location: -341.15, 60.88, -22.09
	Entity's Block location: World: (-342,60,-23), Chunk: (at 10,3,9 in -22,-2; contains blocks -352,0,-32 to -337,255,-17), Region: (-1,-1; contains chunks -32,-32 to -1,-1, blocks -512,0,-512 to -1,255,-1)
	Entity's Momentum: 0.00, 0.00, -0.01
	Entity's Passengers: []
	Entity's Vehicle: ~~ERROR~~ NullPointerException: null
Stacktrace:
	at aug.p_(SourceFile:1475)
	at se.p_(SourceFile:538)

-- Affected level --
Details:
	Level name: Down
	All players: 1 total; [sg['Naunuk2424'/218, l='Down', x=-355.32, y=63.00, z=5.30]]
	Chunk stats: ServerChunkCache: 1466 Drop: 0
	Level seed: 1651194464
	Level generator: ID 00 - default, ver 1. Features enabled: true
	Level generator options: 
	Level spawn location: World: (160,64,104), Chunk: (at 0,4,8 in 10,6; contains blocks 160,0,96 to 175,255,111), Region: (0,0; contains chunks 0,0 to 31,31, blocks 0,0,0 to 511,255,511)
	Level time: 359600 game time, 380349 day time
	Level dimension: 0
	Level storage version: 0x04ABD - Anvil
	Level weather: Rain time: 87997 (now: false), thunder time: 57686 (now: false)
	Level game mode: Game mode: survival (ID 0). Hardcore: true. Cheats: false
Stacktrace:
	at net.minecraft.server.MinecraftServer.w(SourceFile:702)
	at net.minecraft.server.MinecraftServer.v(SourceFile:627)
	at czd.v(SourceFile:155)
	at net.minecraft.server.MinecraftServer.run(SourceFile:532)
	at java.lang.Thread.run(Thread.java:745)

-- System Details --
Details:
	Minecraft Version: 18w11a
	Operating System: Windows 10 (amd64) version 10.0
	Java Version: 1.8.0_25, Oracle Corporation
	Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Oracle Corporation
	Memory: 260467800 bytes (248 MB) / 603979776 bytes (576 MB) up to 4294967296 bytes (4096 MB)
	JVM Flags: 8 total; -XX:HeapDumpPath=MojangTricksIntelDriversForPerformance_javaw.exe_minecraft.exe.heapdump -Xmx4G -XX:+UnlockExperimentalVMOptions -XX:+UseG1GC -XX:G1NewSizePercent=20 -XX:G1ReservePercent=20 -XX:MaxGCPauseMillis=50 -XX:G1HeapRegionSize=16M
	Profiler Position: N/A (disabled)
	Player Count: 1 / 8; [sg['Naunuk2424'/218, l='Down', x=-355.32, y=63.00, z=5.30]]
	Data Packs: vanilla
	Type: Integrated Server (map_client.txt)
	Is Modded: Probably not. Jar signature remains and both client + server brands are untouched.