Somehow when Inventory tweaks is loaded the Minecraft client does not startup.

Using the following Components

• MagicLauncher 1.1.6

Mods:

• minecraftforge-universal-1.6.2-9.10.0.789
• InventoryTweaks-MC1.6.2-1.55-b56

It is a clean minecraft install and selected the 1.6.2 version

This works:

This crashes the client

---- Minecraft Crash Report ----
// Oops.

Time: 7/16/13 10:14 AM
Description: Initializing game

java.lang.NullPointerException
at bka.b(SourceFile:76)
at ats.O(SourceFile:332)
at ats.d(SourceFile:599)
at net.minecraft.client.main.Main.main(SourceFile:101)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at magic.launcher.Launcher.main(Unknown Source)

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

-- Head --
Stacktrace:
at bka.b(SourceFile:76)
at ats.O(SourceFile:332)

-- Initialization --
Details:
Stacktrace:
at ats.d(SourceFile:599)
at net.minecraft.client.main.Main.main(SourceFile:101)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at magic.launcher.Launcher.main(Unknown Source)

-- System Details --
Details:
Minecraft Version: 1.6.2
Operating System: Mac OS X (x86_64) version 10.9
Java Version: 1.6.0_51, Apple Inc.
Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Apple Inc.
Memory: 481778608 bytes (459 MB) / 530186240 bytes (505 MB) up to 530186240 bytes (505 MB)
JVM Flags: 2 total; -Xms512m -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: 1.6.2
LWJGL: 2.9.0
OpenGL: AMD Radeon HD 6770M OpenGL Engine GL version 2.1 ATI-1.12.42, ATI Technologies Inc.
Is Modded: Very likely; Jar signature invalidated
Type: Client (map_client.txt)
Resource Pack: Default
Current Language: ERROR NullPointerException: null
Profiler Position: N/A (disabled)
Vec3 Pool Size: ERROR NullPointerException: null

Thanks for your support and Feedback: while the Forge plugin was able to load this way, prior to 1.6. Indeed you now have to install it and use the Forge profile.
Then by adding invtweaks to the mods folder works..

This renders the use for MagicLauncher quit useless in my opinion. I used to to connect to 1.4, 1.5 and now 1.6 servers. I'll need to write them (or him).

Thanks again.

You need invtweaks in the external mods section.

Forge is not installed correctly, use the installer and the Forge profile it creates as the base for adding mods.