So, I was testing my Forge on Magic Launcher and discovered a bug. Here's my log:
*** MagicMinecraftLauncher 1.0.0 ***
Disable inactive mods
2013-01-27 20:19:14 [iNFO] [ForgeModLoader] Forge Mod Loader version 4.7.4.520 for Minecraft 1.4.7 loading
2013-01-27 20:19:16 [iNFO] [ForgeModLoader] Found valid fingerprint for Minecraft Forge. Certificate fingerprint de4cf8a3f3bc15635810044c39240bf96804ea7d
2013-01-27 20:19:16 [sEVERE] [ForgeModLoader] This version of FML is built for Minecraft 1.4.7, we have detected Minecraft 12w50a in your minecraft jar file
2013-01-27 20:19:16 [iNFO] [sTDOUT] A CRITICAL PROBLEM OCCURED INITIALIZING MINECRAFT - LIKELY YOU HAVE AN INCORRECT VERSION FOR THIS FML
2013-01-27 20:21:36 [iNFO] [sTDERR] java.lang.reflect.InvocationTargetException
2013-01-27 20:21:36 [iNFO] [sTDERR] at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
2013-01-27 20:21:36 [iNFO] [sTDERR] at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
2013-01-27 20:21:36 [iNFO] [sTDERR] at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
2013-01-27 20:21:36 [iNFO] [sTDERR] at java.lang.reflect.Method.invoke(Unknown Source)
2013-01-27 20:21:36 [iNFO] [sTDERR] at magic.launcher.Launcher.main(Unknown Source)
2013-01-27 20:21:36 [iNFO] [sTDERR] Caused by: java.lang.RuntimeException: java.lang.RuntimeException: java.lang.reflect.InvocationTargetException
2013-01-27 20:21:36 [iNFO] [sTDERR] at cpw.mods.fml.relauncher.FMLRelauncher.setupHome(FMLRelauncher.java:175)
2013-01-27 20:21:36 [iNFO] [sTDERR] at cpw.mods.fml.relauncher.FMLRelauncher.relaunchClient(FMLRelauncher.java:92)
2013-01-27 20:21:36 [iNFO] [sTDERR] at cpw.mods.fml.relauncher.FMLRelauncher.handleClientRelaunch(FMLRelauncher.java:26)
2013-01-27 20:21:36 [iNFO] [sTDERR] at net.minecraft.client.Minecraft.main(Minecraft.java:2235)
2013-01-27 20:21:36 [iNFO] [sTDERR] ... 5 more
2013-01-27 20:21:36 [iNFO] [sTDERR] Caused by: java.lang.RuntimeException: java.lang.reflect.InvocationTargetException
2013-01-27 20:21:36 [iNFO] [sTDERR] at cpw.mods.fml.relauncher.RelaunchLibraryManager.handleLaunch(RelaunchLibraryManager.java:291)
2013-01-27 20:21:36 [iNFO] [sTDERR] at cpw.mods.fml.relauncher.FMLRelauncher.setupHome(FMLRelauncher.java:155)
2013-01-27 20:21:36 [iNFO] [sTDERR] ... 8 more
2013-01-27 20:21:36 [iNFO] [sTDERR] Caused by: java.lang.reflect.InvocationTargetException
2013-01-27 20:21:36 [iNFO] [sTDERR] at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
2013-01-27 20:21:36 [iNFO] [sTDERR] at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
2013-01-27 20:21:36 [iNFO] [sTDERR] at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
2013-01-27 20:21:36 [iNFO] [sTDERR] at java.lang.reflect.Method.invoke(Unknown Source)
2013-01-27 20:21:36 [iNFO] [sTDERR] at cpw.mods.fml.relauncher.RelaunchLibraryManager.handleLaunch(RelaunchLibraryManager.java:283)
2013-01-27 20:21:36 [iNFO] [sTDERR] ... 9 more
2013-01-27 20:21:36 [iNFO] [sTDERR] Caused by: cpw.mods.fml.common.LoaderException
2013-01-27 20:21:36 [iNFO] [sTDERR] at cpw.mods.fml.common.Loader.<init>(Loader.java:176)
2013-01-27 20:21:36 [iNFO] [sTDERR] at cpw.mods.fml.common.Loader.instance(Loader.java:151)
2013-01-27 20:21:36 [iNFO] [sTDERR] ... 14 more