The bug
If the player makes a preset for superflat that goes over the build limit, the game hangs on the loading screen.
Example preset:
minecraft:bedrock,255*minecraft:dirt,minecraft:grass;1;
Crash report
1.13.1\: [^crash-2018-08-26_12.24.23-client.txt]
Description: mouseClicked event handler
java.lang.ArrayIndexOutOfBoundsException: 256
at buc.w(SourceFile:205)
at buc.b(SourceFile:383)
at cjl.a(SourceFile:70)
at cjz$1.a(SourceFile:170)
at cgt.mouseClicked(SourceFile:103)
at chp.mouseClicked(SourceFile:46)
at cfu.b(SourceFile:83)
at cfu$$Lambda$1007/1799068185.run(Unknown Source)
at ckc.a(SourceFile:430)
at cfu.a(SourceFile:83)
at cfu$$Lambda$839/270276013.invoke(Unknown Source)
at org.lwjgl.glfw.GLFWMouseButtonCallbackI.callback(GLFWMouseButtonCallbackI.java:36)
at org.lwjgl.system.JNI.invokeV(Native Method)
at org.lwjgl.glfw.GLFW.glfwWaitEventsTimeout(GLFW.java:3108)
at cgc.a(SourceFile:321)
at cfs.c(SourceFile:875)
at cfs.a(SourceFile:395)
at net.minecraft.client.main.Main.main(SourceFile:144)
Linked issues
is duplicated by
relates to
Attachments
Comments

Confirmed for
Minecraft 1.8-pre 1
Minecraft 1.8.1-pre3

Confirmed for
15w37a
Example preset
3;minecraft:bedrock,255*minecraft:dirt,minecraft:grass;1;
Error
[15:43:46] [Server thread/INFO]: Starting integrated minecraft server version 15w37a
[15:43:46] [Server thread/INFO]: Generating keypair
[15:43:47] [Server thread/ERROR]: Encountered an unexpected exception
java.lang.ArrayIndexOutOfBoundsException: 256
at asc.<init>(SourceFile:101) ~[15w37a.jar:?]
at arq.c(SourceFile:68) ~[15w37a.jar:?]
at lk.m(SourceFile:695) ~[15w37a.jar:?]
at lk.<init>(SourceFile:138) ~[15w37a.jar:?]
at bvm.a(SourceFile:98) ~[15w37a.jar:?]
at bvm.j(SourceFile:130) ~[15w37a.jar:?]
at net.minecraft.server.MinecraftServer.run(SourceFile:420) [15w37a.jar:?]
at java.lang.Thread.run(Thread.java:745) [?:1.8.0_25]
[15:43:47] [Server thread/ERROR]: This crash report has been saved to: ###\crash-reports\crash-2015-09-11_15.43.47-server.txt
[15:43:47] [Server thread/INFO]: Stopping server
[15:43:47] [Server thread/INFO]: Saving players
[15:43:47] [Server thread/INFO]: Saving worlds
[15:43:47] [Server thread/ERROR]: Exception stopping the server
java.lang.NullPointerException
at net.minecraft.server.MinecraftServer.u(SourceFile:393) ~[15w37a.jar:?]
at bvm.u(SourceFile:323) ~[15w37a.jar:?]
at net.minecraft.server.MinecraftServer.run(SourceFile:483) [15w37a.jar:?]
at java.lang.Thread.run(Thread.java:745) [?:1.8.0_25]
Server crash
---- Minecraft Crash Report ----
// Would you like a cupcake?
Time: 11.09.15 15:43
Description: Exception in server tick loop
java.lang.ArrayIndexOutOfBoundsException: 256
at asc.<init>(SourceFile:101)
at arq.c(SourceFile:68)
at lk.m(SourceFile:695)
at lk.<init>(SourceFile:138)
at bvm.a(SourceFile:98)
at bvm.j(SourceFile:130)
at net.minecraft.server.MinecraftServer.run(SourceFile:420)
at java.lang.Thread.run(Thread.java:745)
A detailed walkthrough of the error, its code path and all known details is as follows:
---------------------------------------------------------------------------------------
-- System Details --
Details:
Minecraft Version: 15w37a
Operating System: Windows 7 (amd64) version 6.1
Java Version: 1.8.0_25, Oracle Corporation
Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Oracle Corporation
Memory: 583688080 bytes (556 MB) / 786272256 bytes (749 MB) up to 1060372480 bytes (1011 MB)
JVM Flags: 6 total; -XX:HeapDumpPath=MojangTricksIntelDriversForPerformance_javaw.exe_minecraft.exe.heapdump -Xmx1G -XX:+UseConcMarkSweepGC -XX:+CMSIncrementalMode -XX:-UseAdaptiveSizePolicy -Xmn128M
IntCache: cache: 1, tcache: 1, allocated: 12, tallocated: 94
Profiler Position: N/A (disabled)
Player Count: 0 / 8; []
Type: Integrated Server (map_client.txt)
Is Modded: Probably not. Jar signature remains and both client + server brands are untouched.
affect 1.13 release

Can no longer reproduce in 19w38b. Someone else please check. Didn't test it with 1.14.4.

Fixed in 1.14.4-pre1

Confirmed fixed; the blocks above it will have their count set to 0 (which makes sense and doesn't lose information)
Well, Minecraft's maximum build height is 256, so when the game tries to place blocks above that, it crashes. Also, please don't give us the output of the console, but give us the crash report from
C:\Users\Logan\AppData\Roaming\.minecraft\crash-reports\crash-2014-08-18_17.17.46-server.txt
instead (the link to the crash report is always in the output). But I agree that Minecraft should not allow you to do this, instead of crashing.