EntityCollision

Ah I forgot to mention I am using 1.5.2 because I would like to make some changes to a Voltz mod (technic pack). This still runs on MC 1.5.2 I am aware that it won't be compatible with the newer MC versions but it is possible to develop mods for 1.5.2 so I was hoping someone recognized this error and was able to tell me what's going on.

Hi, I've set up my dev environment following the steps on the wiki: http://www.minecraftforge.net/wiki/Forge_Development_in_IntelliJ_IDEA#For_Minecraft_1.5_and_earlier But when I try to launch using the client configuration the launcher crashes. Log: https://gist.github.com/Flightkick/9c8b4de423760f278691df62088cba2f What could cause the ClassNotFoundExceptions and how may I be able to solve this? Thanks in advance.