[MC-173153] Server creeper

I encountered a bug caused by a creeper spawn egg, which crashes Minecaft servers when you put it into dispensers. A friend of mine used it on my server and it crashed immediately.

This is the NBT data of the item. I got it using /data get entity @s SelectedItem

{id: "minecraft:creeper_spawn_egg", Count: 2b, tag: {EntityTag: {id: "Creeper", CustomName: "TEST", CustomNameVisible: 1}, display: {Lore: ['"§r1. Place item in dispenser."', '"§r2. Dispense item."', '"§r3. Ssss... BOOM!"'], Name: '{"text":"§rServer Creeper"}'}}}

My friend told me that he used a Hacked client to get the item.

I tested it out on a single player world and the crash report said:
---- Minecraft Crash Report ----
// There are four lights!
Time: 26-2-20 18:06
Description: Loading entity NBT
com.google.gson.JsonSyntaxException: com.google.gson.stream.MalformedJsonException: Use JsonReader.setLenient(true) to accept malformed JSON at line 1 column 1 path $
at com.google.gson.internal.Streams.parse(Streams.java:60)
at com.google.gson.internal.bind.TreeTypeAdapter.read(TreeTypeAdapter.java:65)
at abo.a(SourceFile:494)
at abo.a(SourceFile:519)
at lh$a.a(SourceFile:399)
at alf.f(SourceFile:1574)
at alj.a(SourceFile:375)
at alj.b(SourceFile:342)
at alj.a(SourceFile:300)
at alj.a(SourceFile:291)
at gm$22.a(SourceFile:187)
at gl.dispense(SourceFile:15)
at bsx.a(SourceFile:94)
at bsx.a(SourceFile:117)
at cax.a(SourceFile:267)
at xg.b(SourceFile:585)
at xg$$Lambda$3126/417205785.accept(Unknown Source)
at bmh.b(SourceFile:87)
at xg.a(SourceFile:329)
at net.minecraft.server.MinecraftServer.b(SourceFile:861)
at net.minecraft.server.MinecraftServer.a(SourceFile:800)
at egt.a(SourceFile:130)
at net.minecraft.server.MinecraftServer.run(SourceFile:659)
at java.lang.Thread.run(Thread.java:745)
Caused by: com.google.gson.stream.MalformedJsonException: Use JsonReader.setLenient(true) to accept malformed JSON at line 1 column 1 path $
at com.google.gson.stream.JsonReader.syntaxError(JsonReader.java:1559)
at com.google.gson.stream.JsonReader.checkLenient(JsonReader.java:1401)
at com.google.gson.stream.JsonReader.doPeek(JsonReader.java:593)
at com.google.gson.stream.JsonReader.peek(JsonReader.java:425)
at com.google.gson.internal.Streams.parse(Streams.java:46)
... 23 more

A detailed walkthrough of the error, its code path and all known details is as follows:
---------------------------------------------------------------------------------------
– Head –
Thread: Server thread
Stacktrace:
at com.google.gson.internal.Streams.parse(Streams.java:60)
at com.google.gson.internal.bind.TreeTypeAdapter.read(TreeTypeAdapter.java:65)
at abo.a(SourceFile:494)
at abo.a(SourceFile:519)
at lh$a.a(SourceFile:399)
– Entity being loaded –
Details:
Entity Type: minecraft:creeper (axz)
Entity ID: 212
Entity Name: Â§rServer Creeper
Entity's Exact location: 1898.50, 75.00, 1720.50
Entity's Block location: World: (1898,75,1720), Chunk: (at 10,4,8 in 118,107; contains blocks 1888,0,1712 to 1903,255,1727), Region: (3,3; contains chunks 96,96 to 127,127, blocks 1536,0,1536 to 2047,255,2047)
Entity's Momentum: 0.00, 0.00, 0.00
Entity's Passengers: []
Entity's Vehicle: ~_ERROR~ NullPointerException: null
Stacktrace:
at alf.f(SourceFile:1574)
at alj.a(SourceFile:375)
at alj.b(SourceFile:342)
at alj.a(SourceFile:300)
at alj.a(SourceFile:291)
at gm$22.a(SourceFile:187)
at gl.dispense(SourceFile:15)
at bsx.a(SourceFile:94)
at bsx.a(SourceFile:117)
at cax.a(SourceFile:267)
at xg.b(SourceFile:585)
at xg$$Lambda$3126/417205785.accept(Unknown Source)
– Block being ticked –
Details:
Block location: World: (1897,75,1720), Chunk: (at 9,4,8 in 118,107; contains blocks 1888,0,1712 to 1903,255,1727), Region: (3,3; contains chunks 96,96 to 127,127, blocks 1536,0,1536 to 2047,255,2047)
Stacktrace:
at bmh.b(SourceFile:87)
at xg.a(SourceFile:329)
– Affected level –
Details:
All players: 1 total; [xh['thijmer'/34, l='1.16 snapshot test', x=1899.27, y=75.00, z=1718.71]]
Chunk stats: ServerChunkCache: 3969
Level dimension: minecraft:the_nether
Derived: true
Level name: 1.16 snapshot test
Level seed: 6609845154068785934
Level generator: ID 00 - default, ver 1. Features enabled: true
Level generator options: {}
Level spawn location: World: (-80,63,-211), Chunk: (at 0,3,13 in -5,-14; contains blocks -80,0,-224 to -65,255,-209), Region: (-1,-1; contains chunks -32,-32 to -1,-1, blocks -512,0,-512 to -1,255,-1)
Level time: 93293 game time, 93293 day time
Known server brands: vanilla
Level was modded: false
Level storage version: 0x04ABD - Anvil
Level weather: Rain time: 32361 (now: false), thunder time: 28202 (now: false)
Level game mode: Game mode: creative (ID 1). Hardcore: false. Cheats: true
Stacktrace:
at net.minecraft.server.MinecraftServer.b(SourceFile:861)
at net.minecraft.server.MinecraftServer.a(SourceFile:800)
at egt.a(SourceFile:130)
at net.minecraft.server.MinecraftServer.run(SourceFile:659)
at java.lang.Thread.run(Thread.java:745)
– System Details –
Details:
Minecraft Version: 20w08a
Minecraft Version ID: 20w08a
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: 651887408 bytes (621 MB) / 1912602624 bytes (1824 MB) up to 2147483648 bytes (2048 MB)
CPUs: 16
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: 1 / 8; [xh['thijmer'/34, l='1.16 snapshot test', x=1899.27, y=75.00, z=1718.71]]
Data Packs: vanilla
Type: Integrated Server (map_client.txt)
Is Modded: Probably not. Jar signature remains and both client + server brands are untouched.