Hopper: java.lang.StringIndexOutOfBoundsException: String index out of range: -1

java.lang.StringIndexOutOfBoundsException: String index out of range: -1
	at java.lang.String.charAt(Unknown Source)
	at blq.a(SourceFile:42)
	at bln.c(SourceFile:165)
	at bln.a(SourceFile:100)
	at bln.h(SourceFile:81)
	at bln.<init>(SourceFile:62)
	at atv.O(SourceFile:323)

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

Time: 21/09/13 12:09
Description: Initializing game

java.lang.StringIndexOutOfBoundsException: String index out of range: -1
	at java.lang.String.charAt(Unknown Source)
	at blq.a(SourceFile:42)
	at bln.c(SourceFile:165)
	at bln.a(SourceFile:100)
	at bln.h(SourceFile:81)
	at bln.<init>(SourceFile:62)
	at atv.O(SourceFile:323)
	at atv.d(SourceFile:599)
	at net.minecraft.client.main.Main.main(SourceFile:101)


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

-- Head --
Stacktrace:
	at java.lang.String.charAt(Unknown Source)
	at blq.a(SourceFile:42)
	at bln.c(SourceFile:165)
	at bln.a(SourceFile:100)
	at bln.h(SourceFile:81)
	at bln.<init>(SourceFile:62)
	at atv.O(SourceFile:323)

-- Initialization --
Details:
Stacktrace:
	at atv.d(SourceFile:599)
	at net.minecraft.client.main.Main.main(SourceFile:101)

-- System Details --
Details:
	Minecraft Version: 1.6.4
	Operating System: Windows 7 (x86) version 6.1
	Java Version: 1.6.0_24, Sun Microsystems Inc.
	Java VM Version: Java HotSpot(TM) Client VM (mixed mode, sharing), Sun Microsystems Inc.
	Memory: 8603136 bytes (8 MB) / 26808320 bytes (25 MB) up to 518979584 bytes (494 MB)
	JVM Flags: 2 total; -XX:HeapDumpPath=MojangTricksIntelDriversForPerformance_javaw.exe_minecraft.exe.heapdump -Xmx512M
	AABB Pool Size: 0 (0 bytes; 0 MB) allocated, 0 (0 bytes; 0 MB) used
	Suspicious classes: No suspicious classes found.
	IntCache: cache: 0, tcache: 0, allocated: 0, tallocated: 0
	Launched Version: 1.6.4
	LWJGL: 2.9.0
	OpenGL: GeForce 8400 GS/PCIe/SSE2 GL version 3.3.0, NVIDIA Corporation
	Is Modded: Probably not. Jar signature remains and client brand is untouched.
	Type: Client (map_client.txt)
	Resource Pack: Default
	Current Language: Français (CA)
	Profiler Position: N/A (disabled)
	Vec3 Pool Size: ~~ERROR~~ NullPointerException: null