When you kill a parrot the new version it crashes. at first I thought it was specific though because I was on a superflat surrounded by noteblocks when it happened the first time but after further testing it is just when you kill a parrot.

The error code it shows:

---- Minecraft Crash Report ----
// Why is it breaking

Time: 10/4/19 8:33 AM
Description: Unexpected error

java.lang.NullPointerException: Unexpected error
at atd.a(SourceFile:407)
at axx.f(SourceFile:1234)
at dmq.a(SourceFile:363)
at das.aE(SourceFile:1234)
at das.aG(SourceFile:1517)
at das.n(SourceFile:1367)
at das.d(SourceFile:907)
at das.b(SourceFile:569)
at net.minecraft.client.main.Main.main(SourceFile:199)

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

– Head –
Thread: Render thread
Stacktrace:
at atd.a(SourceFile:407)
at axx.f(SourceFile:1234)
at dmq.a(SourceFile:363)
at das.aE(SourceFile:1234)
at das.aG(SourceFile:1517)

– Affected level –
Details:
All players: 1 total; [dpb['RawrRarRawr'/342, l='MpServer', x=12.03, y=71.00, z=61.11]]
Chunk stats: Client Chunk Cache: 729, 483
Level dimension: minecraft:overworld
Level name: MpServer
Level seed: 2647974136041811902
Level generator: ID 00 - default, ver 1. Features enabled: false
Level generator options: {}
Level spawn location: World: (0,69,7), Chunk: (at 0,4,7 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: 5237 game time, 5237 day time
Level storage version: 0x00000 - Unknown?
Level weather: Rain time: 0 (now: false), thunder time: 0 (now: false)
Level game mode: Game mode: creative (ID 1). Hardcore: false. Cheats: false
Server brand: vanilla
Server type: Integrated singleplayer server
Stacktrace:
at dmr.a(SourceFile:419)
at das.c(SourceFile:1842)
at das.b(SourceFile:589)
at net.minecraft.client.main.Main.main(SourceFile:199)

– System Details –
Details:
Minecraft Version: 19w40a
Minecraft Version ID: 19w40a
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: 1039143688 bytes (991 MB) / 2080374784 bytes (1984 MB) up to 2147483648 bytes (2048 MB)
CPUs: 4
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
Launched Version: 19w40a
Backend library: LWJGL version 3.2.2 build 10
Backend API: GeForce GTX 1050/PCIe/SSE2 GL version 4.6.0 NVIDIA 390.65, NVIDIA Corporation
GL Caps: Using framebuffer using OpenGL 3.0
Using VBOs: Yes
Is Modded: Probably not. Jar signature remains and client brand is untouched.
Type: Client (map_client.txt)
Resource Packs:
Current Language: LOLCAT (Kingdom of Cats)
CPU: 4x Intel(R) Core(TM) i5-7400 CPU @ 3.00GHz

The thing it says on the thing before you open the crash report:

The game crashed whilst unexpected error
Error: java.lang.NullPointerException: Unexpected error