Minecraft crashes if connection is lost when editing signs

  Minecraft has crashed!      
      ----------------------      

Minecraft has stopped running because it encountered a problem; Unexpected error
This error has been saved to /Users/alex/Library/Application Support/minecraft/crash-reports/crash-2012-11-01_11.55.14-client.txt for your convenience. Please include a copy of this file if you report this crash to anyone.



--- BEGIN ERROR REPORT d05ba18d --------
Generated 11/1/12 11:55 AM

- Minecraft Version: 1.4.2
- Operating System: Mac OS X (x86_64) version 10.7.4
- Java Version: 1.6.0_33, Apple Inc.
- Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Apple Inc.
- Memory: 509633880 bytes (486 MB) / 554369024 bytes (528 MB) up to 1069416448 bytes (1019 MB)
- JVM Flags: 3 total; -Xbootclasspath/a:/System/Library/PrivateFrameworks/JavaApplicationLauncher.framework/Resources/LauncherSupport.jar -Xms512M -Xmx1024M
- AABB Pool Size: 245 (13720 bytes; 0 MB) allocated, 120 (6720 bytes; 0 MB) used
- LWJGL: 2.4.2
- OpenGL: NVIDIA GeForce 320M OpenGL Engine GL version 2.1 NVIDIA-7.18.18, NVIDIA Corporation
- Is Modded: Probably not
- Type: Client
- Texture Pack: Default
- Profiler Position: N/A (disabled)
- Vec3 Pool Size: ~ERROR~ NullPointerException: null

java.lang.NullPointerException
	at auo.b(SourceFile:42)
	at net.minecraft.client.Minecraft.a(SourceFile:433)
	at awr.a(SourceFile:492)
	at bx.b(SourceFile:347)
	at awr.d(SourceFile:98)
	at awz.b(SourceFile:61)
	at net.minecraft.client.Minecraft.l(SourceFile:1282)
	at net.minecraft.client.Minecraft.J(SourceFile:582)
	at net.minecraft.client.Minecraft.run(SourceFile:534)
	at java.lang.Thread.run(Thread.java:680)
--- END ERROR REPORT efe924ed ----------