[MC-145102] "--server" client launch argument may crash the client on the loading screen

Before 19w08a, the client would start connecting to the server after the loading screen is complete. As of 19w08a, it appears the client will attempt to connect to the server BEFORE the loading screen is complete.

If the connection is established before the loading screen is complete, the client will crash on the loading screen. It appears to fail by attempting to render the world too early. A crash report is attached.

It should be possible to reproduce by attempting to connect to a running local server (although setting up the launch arguments is a bit finnicky with the launcher). With some precise timing it is also possible to launch both the server and client simultaneously so that the connection is established AFTER the loading screen is complete, in which case there will be no crash.

19w09a: crash-2019-02-27_23.13.28-client.txt

---- Minecraft Crash Report ----
// Don't be sad, have a hug! <3

Time: 27.02.19 23:13
Description: Tesselating block in world

java.lang.NullPointerException: Tesselating block in world
	at dhc.a(SourceFile:42)
	at dha.a(SourceFile:60)
	at djc.b(SourceFile:220)
	at diz.a(SourceFile:88)
	at diy.b(SourceFile:137)
	at dgk.a(SourceFile:907)
	at dgg.b(SourceFile:929)
	at dgg.a(SourceFile:865)
	at dgg.a(SourceFile:725)
	at cqx.d(SourceFile:951)
	at cqx.b(SourceFile:412)
	at net.minecraft.client.main.Main.main(SourceFile:154)


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

-- Head --
Thread: Client thread
Stacktrace:
	at dhc.a(SourceFile:42)

-- Block being tesselated --
Details:
	Block: Block{minecraft:stone}
	Block location: World: (-272,64,-144), Chunk: (at 0,4,0 in -17,-9; contains blocks -272,0,-144 to -257,255,-129), Region: (-1,-1; contains chunks -32,-32 to -1,-1, blocks -512,0,-512 to -1,255,-1)
Stacktrace:
	at dha.a(SourceFile:60)
	at djc.b(SourceFile:220)
	at diz.a(SourceFile:88)
	at diy.b(SourceFile:137)
	at dgk.a(SourceFile:907)
	at dgg.b(SourceFile:929)
	at dgg.a(SourceFile:865)

-- Affected level --
Details:
	Level name: MpServer
	All players: 1 total; [dft['JamiesWhiteShirt'/999, l='MpServer', x=-249.50, y=71.00, z=-139.50]]
	Chunk stats: MultiplayerChunkCache: 1089, 183
	Level seed: 0
	Level generator: ID 00 - default, ver 1. Features enabled: false
	Level generator options: {}
	Level spawn location: World: (8,64,8), Chunk: (at 8,4,8 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: 3 game time, 3 day time
	Level dimension: 0
	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: Non-integrated multiplayer server
Stacktrace:
	at ddj.a(SourceFile:449)
	at cqx.b(SourceFile:1920)
	at cqx.b(SourceFile:420)
	at net.minecraft.client.main.Main.main(SourceFile:154)

-- System Details --
Details:
	Minecraft Version: 19w09a
	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: 1365344272 bytes (1302 MB) / 2113929216 bytes (2016 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
	Launched Version: 19w09a-server
	LWJGL: 3.2.1 build 12
	OpenGL: GeForce GTX 1080/PCIe/SSE2 GL version 4.6.0 NVIDIA 417.71, NVIDIA Corporation
	GL Caps: Using GL 1.3 multitexturing.
Using GL 1.3 texture combiners.
Using framebuffer objects because OpenGL 3.0 is supported and separate blending is supported.
Shaders are available because OpenGL 2.1 is supported.
VBOs are available because OpenGL 1.5 is supported.

	Using VBOs: Yes
	Is Modded: Probably not. Jar signature remains and client brand is untouched.
	Type: Client (map_client.txt)
	Resource Packs: 
	Current Language: English (US)
	CPU: 4x Intel(R) Core(TM) i5-6600K CPU @ 3.50GHz