Hopper: java.lang.NullPointerException

java.lang.NullPointerException
	at java.util.HashMap.putAll(Unknown Source)
	at le.a(SourceFile:38)
	at hx.j(SourceFile:757)
	at kg.<init>(SourceFile:75)
	at hx.a(SourceFile:287)
	at bnj.b(SourceFile:67)
	at net.minecraft.server.MinecraftServer.t(SourceFile:481)
	at net.minecraft.server.MinecraftServer.s(SourceFile:398)
	at bng.s(SourceFile:124)
	at net.minecraft.server.MinecraftServer.run(SourceFile:332)
	at hs.run(SourceFile:575)

---- Minecraft Crash Report ----
// You should try our sister game, Minceraft!

Time: 05/09/13 05:02 م
Description: Exception in server tick loop

java.lang.NullPointerException
	at java.util.HashMap.putAll(Unknown Source)
	at le.a(SourceFile:38)
	at hx.j(SourceFile:757)
	at kg.<init>(SourceFile:75)
	at hx.a(SourceFile:287)
	at bnj.b(SourceFile:67)
	at net.minecraft.server.MinecraftServer.t(SourceFile:481)
	at net.minecraft.server.MinecraftServer.s(SourceFile:398)
	at bng.s(SourceFile:124)
	at net.minecraft.server.MinecraftServer.run(SourceFile:332)
	at hs.run(SourceFile:575)


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

-- System Details --
Details:
	Minecraft Version: 13w36a
	Operating System: Windows Vista (x86) version 6.0
	Java Version: 1.7.0_25, Oracle Corporation
	Java VM Version: Java HotSpot(TM) Client VM (mixed mode, sharing), Oracle Corporation
	Memory: 23592368 bytes (22 MB) / 112644096 bytes (107 MB) up to 518979584 bytes (494 MB)
	JVM Flags: 2 total; -XX:HeapDumpPath=MojangTricksIntelDriversForPerformance_javaw.exe_minecraft.exe.heapdump -Xmx512M
	AABB Pool Size: 1163 (65128 bytes; 0 MB) allocated, 1092 (61152 bytes; 0 MB) used
	Suspicious classes: [com.ibm.icu.text.ArabicShapingException], [gnu.trove.TIntCollection], [gnu.trove.impl.HashFunctions, PrimeFinder], [gnu.trove.impl.hash.THash, TPrimitiveHash, TIntIntHash], [gnu.trove.iterator.TIterator, TAdvancingIterator, TIntIntIterator], [gnu.trove.map.TIntIntMap], [gnu.trove.map.hash.TIntIntHashMap], [gnu.trove.procedure.TIntIntProcedure], [gnu.trove.set.TIntSet]
	IntCache: cache: 0, tcache: 0, allocated: 12, tallocated: 94
	Profiler Position: N/A (disabled)
	Vec3 Pool Size: 147 (8232 bytes; 0 MB) allocated, 147 (8232 bytes; 0 MB) used
	Player Count: 0 / 8; []
	Type: Integrated Server (map_client.txt)
	Is Modded: Probably not. Jar signature remains and both client + server brands are untouched.