The launcher treats most crash report as "modded" (except manually forced crash), maybe because the bottom part of the crash report is missing.
Linked issues
is duplicated by
Attachments
Comments

Affects hopper too : http://hopper.minecraft.net/crashes/minecraft/MCX-1752010/69677823/
Crash: MCX-1752010 - java.lang.IndexOutOfBoundsException
Minecraft Version: 14w30b
Reported Date: July 24, 2014, 3:29 a.m.
Operating System: 'Linux' (version '3.13.0-30-generic')
Java Version: 1.7.0_65
Client: Modded
Server: Vanilla
Confirmed