demo version crash

--- BEGIN ERROR REPORT 714dc82e --------
Full report at:
/Users/paulmccourt/Library/Application Support/minecraft/crash-reports/crash-2013-06-03_20.10.45-server.txt
Please show that file to Mojang, NOT just this screen!

Generated 6/3/13 8:11 PM

-- Head --
Stacktrace:
	at ch.b(SourceFile:107)
	at ch.a(SourceFile:39)

-- Packet being sent --
Details:
	Packet ID: 4
	Packet class: fh
Stacktrace:
	at jh.b(SourceFile:430)
	at gu.b(SourceFile:669)
	at gu.a(SourceFile:79)
	at bjj.b(SourceFile:73)
	at net.minecraft.server.MinecraftServer.r(SourceFile:480)
	at net.minecraft.server.MinecraftServer.q(SourceFile:397)
	at bjg.q(SourceFile:122)
	at net.minecraft.server.MinecraftServer.run(SourceFile:331)
	at gp.run(SourceFile:573)

-- System Details --
Details:
	Minecraft Version: 1.5.2
	Operating System: Mac OS X (x86_64) version 10.6.8
	Java Version: 1.6.0_45, Apple Inc.
	Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Apple Inc.
	Memory: 955509720 bytes (911 MB) / 1069416448 bytes (1019 MB) up to 1069416448 bytes (1019 MB)
	JVM Flags: 3 total; -Xbootclasspath/a:/System/Library/Frameworks/JavaVM.framework/Resources/Deploy.bundle/Contents/Resources/Java/deploy.jar:/System/Library/Frameworks/JavaVM.framework/Resources/Deploy.bundle/Contents/Resources/Java/javaws.jar:/System/Library/Frameworks/JavaVM.framework/Resources/Deploy.bundle/Contents/Resources/Java/plugin.jar -Xmx1g -Xms1024M
	AABB Pool Size: 548 (30688 bytes; 0 MB) allocated, 548 (30688 bytes; 0 MB) used
	Suspicious classes: No suspicious classes found.
	IntCache: cache: 0, tcache: 0, allocated: 3, tallocated: 63
	Profiler Position: N/A (disabled)
	Vec3 Pool Size: 73 (4088 bytes; 0 MB) allocated, 72 (4032 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.

java.lang.NullPointerException
	at ch.b(SourceFile:107)
	at ch.a(SourceFile:39)
	at jh.b(SourceFile:430)
	at gu.b(SourceFile:669)
	at gu.a(SourceFile:79)
	at bjj.b(SourceFile:73)
	at net.minecraft.server.MinecraftServer.r(SourceFile:480)
	at net.minecraft.server.MinecraftServer.q(SourceFile:397)
	at bjg.q(SourceFile:122)
	at net.minecraft.server.MinecraftServer.run(SourceFile:331)
	at gp.run(SourceFile:573)
--- END ERROR REPORT 2af3a44c ----------