I was making a superflat of 256 layers of stone. I broke the block below me, placed a Random Firework Spawner (included in TooManyItems mod) and it just crashed. When the error report showed up, one of the lines of text said "Show this to Mojang, NOT just this screen!" so that's why I've included the bug report file as the attachment.
MC-6161
Crash Report
Resolved
Duplicate
0
Langston Allen Loff
(Unassigned)
Unconfirmed
Minecraft 1.4.6
Retrieved
This ticket is invalid as it relates to a modded or 3rd party client/server.
Any non-standard client/server build needs to be taken up with the appropriate team, not Mojang.
Any plugin issues need to be addressed to the plugin creator.
This site is for addressing issues related to the base unmodded MineCraft.