What I expected to happen was...:
Nothing special

What actually happened was...:
Game crashed. "Exception ticking world"

Steps to Reproduce:
1. Get slab.
2. Place slab.
3. Step on slab with auto-jump enabled.

---- Minecraft Crash Report ----
// Quite honestly, I wouldn't worry myself about that.

Time: 11.06.16 14:19
Description: Exception ticking world

java.lang.NullPointerException: Exception ticking world
at awy.a(SourceFile:41)
at awu.a(SourceFile:94)
at aty.b(SourceFile:155)
at asv.a(SourceFile:803)
at asv.a(SourceFile:781)
at lr.c(SourceFile:115)
at lx.a(SourceFile:85)
at ly.c(SourceFile:147)
at ls.d(SourceFile:222)
at net.minecraft.server.MinecraftServer.D(SourceFile:618)
at net.minecraft.server.MinecraftServer.C(SourceFile:554)
at bzl.C(SourceFile:155)
at net.minecraft.server.MinecraftServer.run(SourceFile:458)
at java.lang.Thread.run(Unknown Source)

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

– Head –
Thread: Server thread
Stacktrace:
at awy.a(SourceFile:41)
at awu.a(SourceFile:94)
at aty.b(SourceFile:155)
at asv.a(SourceFile:803)
at asv.a(SourceFile:781)
at lr.c(SourceFile:115)
at lx.a(SourceFile:85)
at ly.c(SourceFile:147)
at ls.d(SourceFile:222)

– Affected level –
Details:
Level name: Nowy świat
All players: 1 total; [lu['pitrex29'/77, l='Nowy świat', x=550,20, y=4,00, z=-593,17]]
Chunk stats: ServerChunkCache: 602 Drop: 0
Level seed: 461446490431440576
Level generator: ID 01 - flat, ver 0. Features enabled: true
Level generator options:
Level spawn location: World: (543,4,-581), Chunk: (at 15,0,11 in 33,-37; contains blocks 528,0,-592 to 543,255,-577), Region: (1,-2; contains chunks 32,-64 to 63,-33, blocks 512,0,-1024 to 1023,255,-513)
Level time: 4785 game time, 4785 day time
Level dimension: 0
Level storage version: 0x04ABD - Anvil
Level weather: Rain time: 151911 (now: false), thunder time: 58350 (now: false)
Level game mode: Game mode: creative (ID 1). Hardcore: false. Cheats: true
Stacktrace:
at net.minecraft.server.MinecraftServer.D(SourceFile:618)
at net.minecraft.server.MinecraftServer.C(SourceFile:554)
at bzl.C(SourceFile:155)
at net.minecraft.server.MinecraftServer.run(SourceFile:458)
at java.lang.Thread.run(Unknown Source)

– System Details –
Details:
Minecraft Version: 1.10
Operating System: Windows 7 (amd64) version 6.1
Java Version: 1.8.0_92, Oracle Corporation
Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Oracle Corporation
Memory: 1706512208 bytes (1627 MB) / 2103443456 bytes (2006 MB) up to 2103443456 bytes (2006 MB)
JVM Flags: 2 total; -XX:HeapDumpPath=MojangTricksIntelDriversForPerformance_javaw.exe_minecraft.exe.heapdump -Xms2G
IntCache: cache: 0, tcache: 0, allocated: 0, tallocated: 0
Profiler Position: N/A (disabled)
Player Count: 1 / 8; [lu['pitrex29'/77, l='Nowy świat', x=550,20, y=4,00, z=-593,17]]
Type: Integrated Server (map_client.txt)
Is Modded: Probably not. Jar signature remains and both client + server brands are untouched.