Crash when creating buffet world

The bug

If you create a buffet world the game crash.

How to reproduce

• Go to singleplayer mode

• Click the Create a new world button

• Selecte buffet world for world type

• Click on "Create a new world"

→ ❌  The game crash

Crash report

---- Minecraft Crash Report ----
// Uh... Did I do that?

Time: 27/03/19 19:44
Description: Exception in server tick loop 

n: Non [a-z0-9/._-] character in path of location: minecraft:cye$a$a@4e1c256f
	at qr.<init>(SourceFile:38)
	at qr.<init>(SourceFile:38)
        at bxs.m(SourceFile:100)
	at ve.a(SourceFile:164)
	at ve$$Lambda$2404/175775631.apply(Unknown Source)
	at bgv.<init>(SourceFile:129)
	at ve.<init>(SourceFile:164)
	at net.minecraft.server.MinecraftServer.a(SourceFile:378)
	at dwo.a(SourceFile:82)
	at dwo.d(SourceFile:104)
	at net.minecraft.server.MinecraftServer.run(SourceFile:603)
	at java.lang.Thread.run(Thread.java:745)


A detailed walkthrough of the error, its code path and all known details is as follows:
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-- System Details --
Details:
	Minecraft Version: 19w13a
	Operating System: Windows 10 (amd64) version 10.0
	Java Version: 1.8.0_51, Oracle Corporation
	Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Oracle Corporation
	Memory: 1113594992 bytes (1062 MB) / 2147483648 bytes (2048 MB) up to 2147483648 bytes (2048 MB)
	JVM Flags: 9 total; -XX:HeapDumpPath=MojangTricksIntelDriversForPerformance_javaw.exe_minecraft.exe.heapdump -Xss1M -Xmx2G -XX:+UnlockExperimentalVMOptions -XX:+UseG1GC -XX:G1NewSizePercent=20 -XX:G1ReservePercent=20 -XX:MaxGCPauseMillis=50 -XX:G1HeapRegionSize=32M
	Player Count: 0 / 8; []
	Data Packs: vanilla
	Type: Integrated Server (map_client.txt)
	Is Modded: Probably not. Jar signature remains and both client + server brands are untouched.