java.lang.NullPointerException: Exception in server tick loop

Vanilla SMP with 3 players.

Steps to reproduce: Played normally for 4 hours, occurred seemingly at random and without warning. Players lagged hard, and were then kicked. We were then unable to log back on.

This does not seem to be similar to MC-48411, as it is not a Windows environment, and does not seem to involve slimeblocks.

Server Log:
2014-02-16 21:36:37 [INFO] megashub lost connection: TranslatableComponent{key='disconnect.genericReason', args=[Internal Exception: io.netty.handler.timeout.ReadTimeoutException], siblings=[], style=Style{hasParent=false, color=null, bold=null, italic=null, underlined=null, obfuscated=null, clickEvent=null, hoverEvent=null, insertion=null}}
2014-02-16 21:36:37 [INFO] megashub left the game
2014-02-16 21:37:24 [ERROR] Encountered an unexpected exception
java.lang.NullPointerException
at com.mojang.authlib.GameProfile.hashCode(GameProfile.java:90) ~[minecraft_server.jar:?]
at java.util.WeakHashMap.hash(WeakHashMap.java:365) ~[?:1.7.0_51]
at java.util.WeakHashMap.put(WeakHashMap.java:517) ~[?:1.7.0_51]
at org.apache.commons.lang3.builder.ToStringStyle.register(ToStringStyle.java:191) ~[minecraft_server.jar:?]
at org.apache.commons.lang3.builder.ToStringStyle.appendClassName(ToStringStyle.java:1453) ~[minecraft_server.jar:?]
at org.apache.commons.lang3.builder.ToStringStyle.appendStart(ToStringStyle.java:378) ~[minecraft_server.jar:?]
at org.apache.commons.lang3.builder.ToStringBuilder.<init>(ToStringBuilder.java:263) ~[minecraft_server.jar:?]
at org.apache.commons.lang3.builder.ToStringBuilder.<init>(ToStringBuilder.java:226) ~[minecraft_server.jar:?]
at com.mojang.authlib.GameProfile.toString(GameProfile.java:97) ~[minecraft_server.jar:?]
at ov.d(SourceFile:102) ~[minecraft_server.jar:?]
at ov.a(SourceFile:93) ~[minecraft_server.jar:?]
at ok.c(SourceFile:130) ~[minecraft_server.jar:?]
at net.minecraft.server.MinecraftServer.v(SourceFile:555) ~[minecraft_server.jar:?]
at nb.v(SourceFile:264) ~[minecraft_server.jar:?]
at net.minecraft.server.MinecraftServer.u(SourceFile:471) ~[minecraft_server.jar:?]
at net.minecraft.server.MinecraftServer.run(SourceFile:387) [minecraft_server.jar:?]
at mr.run(SourceFile:657) [minecraft_server.jar:?]

Minecraft Crash Report ----
// Oh - I know what I did wrong!

Time: 2/16/14 9:37 PM
Description: Exception in server tick loop

java.lang.NullPointerException: Exception in server tick loop
at com.mojang.authlib.GameProfile.hashCode(GameProfile.java:90)
at java.util.WeakHashMap.hash(WeakHashMap.java:365)
at java.util.WeakHashMap.put(WeakHashMap.java:517)
at org.apache.commons.lang3.builder.ToStringStyle.register(ToStringStyle.java:191)
at org.apache.commons.lang3.builder.ToStringStyle.appendClassName(ToStringStyle.java:1453)
at org.apache.commons.lang3.builder.ToStringStyle.appendStart(ToStringStyle.java:378)
at org.apache.commons.lang3.builder.ToStringBuilder.<init>(ToStringBuilder.java:263)
at org.apache.commons.lang3.builder.ToStringBuilder.<init>(ToStringBuilder.java:226)
at com.mojang.authlib.GameProfile.toString(GameProfile.java:97)
at ov.d(SourceFile:102)
at ov.a(SourceFile:93)
at ok.c(SourceFile:130)
at net.minecraft.server.MinecraftServer.v(SourceFile:555)
at nb.v(SourceFile:264)
at net.minecraft.server.MinecraftServer.u(SourceFile:471)
at net.minecraft.server.MinecraftServer.run(SourceFile:387)
at mr.run(SourceFile:657)

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

– System Details –
Details:
Minecraft Version: 14w07a
Operating System: Linux (amd64) version 2.6.32-431.3.1.el6.x86_64
Java Version: 1.7.0_51, Oracle Corporation
Java VM Version: OpenJDK 64-Bit Server VM (mixed mode), Oracle Corporation
Memory: 572602760 bytes (546 MB) / 1066926080 bytes (1017 MB) up to 1908932608 bytes (1820 MB)
JVM Flags: 2 total; -Xms1G -Xmx2G
IntCache: cache: 0, tcache: 0, allocated: 12, tallocated: 94
Profiler Position: N/A (disabled)
Player Count: 2 / 10