---- Minecraft Crash Report ----
// I'm sorry, Dave.

Time: 5/20/20 3:42 PM
Description: Exception in server tick loop

java.lang.IllegalArgumentException: value already present: chf@80b33b23
	at com.google.common.collect.HashBiMap.put(HashBiMap.java:287)
	at com.google.common.collect.HashBiMap.put(HashBiMap.java:262)
	at gg.a(SourceFile:51)
	at gg.a(SourceFile:62)
	at gl$a.a(SourceFile:28)
	at net.minecraft.server.MinecraftServer.a(SourceFile:407)
	at net.minecraft.server.MinecraftServer.i_(SourceFile:334)
	at enr.d(SourceFile:65)
	at net.minecraft.server.MinecraftServer.run(SourceFile:666)
	at java.lang.Thread.run(Thread.java:821)


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

-- System Details --
Details:
	Minecraft Version: 20w21a
	Minecraft Version ID: 20w21a
	Operating System: Linux (amd64) version 5.6.12-arch1-1
	Java Version: 1.8.0_242, Eclipse OpenJ9
	Java VM Version: Eclipse OpenJ9 VM (JRE 1.8.0 Linux amd64-64-Bit Compressed References 20200122_511 (JIT enabled, AOT enabled)
OpenJ9   - 51a5857d2
OMR      - 7a1b0239a
JCL      - 8cf8a30581 based on jdk8u242-b08), Eclipse OpenJ9
	Memory: 1614592320 bytes (1539 MB) / 2147483648 bytes (2048 MB) up to 2147483648 bytes (2048 MB)
	CPUs: 8
	JVM Flags: 5 total; -Xoptionsfile=/usr/lib/jvm/java-8-j9/jre/lib/amd64/compressedrefs/options.default -Xlockword:mode=default,noLockword=java/lang/String,noLockword=java/util/MapEntry,noLockword=java/util/HashMap$Entry,noLockword=org/apache/harmony/luni/util/ModifiedMap$Entry,noLockword=java/util/Hashtable$Entry,noLockword=java/lang/invoke/MethodType,noLockword=java/lang/invoke/MethodHandle,noLockword=java/lang/invoke/CollectHandle,noLockword=java/lang/invoke/ConstructorHandle,noLockword=java/lang/invoke/ConvertHandle,noLockword=java/lang/invoke/ArgumentConversionHandle,noLockword=java/lang/invoke/AsTypeHandle,noLockword=java/lang/invoke/ExplicitCastHandle,noLockword=java/lang/invoke/FilterReturnHandle,noLockword=java/lang/invoke/DirectHandle,noLockword=java/lang/invoke/ReceiverBoundHandle,noLockword=java/lang/invoke/DynamicInvokerHandle,noLockword=java/lang/invoke/FieldHandle,noLockword=java/lang/invoke/FieldGetterHandle,noLockword=java/lang/invoke/FieldSetterHandle,noLockword=java/lang/invoke/StaticFieldGetterHandle,noLockword=java/lang/invoke/StaticFieldSetterHandle,noLockword=java/lang/invoke/IndirectHandle,noLockword=java/lang/invoke/InterfaceHandle,noLockword=java/lang/invoke/VirtualHandle,noLockword=java/lang/invoke/PrimitiveHandle,noLockword=java/lang/invoke/InvokeExactHandle,noLockword=java/lang/invoke/InvokeGenericHandle,noLockword=java/lang/invoke/VarargsCollectorHandle,noLockword=java/lang/invoke/ThunkTuple -Xjcl:jclse29 -Xms2048m -Xmx2048m
	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.