Running NEI in a forge dev environment causes that error on loading a world (clientside). It doesn't really crash so there is no crashlog. Instead the server shuts down normally due to the player being disconnected and the client gets booted to the server selector after a "fatal error" screen. I've cut out the stacktrace from the log and put it on pastebin here.
EDIT: After a couple of crashes I've noticed that the crashes happen when processing mob spawners or when processing mob eggs. It seems to be an even 50/50 chance and I haven't seen the crash happen anywhere else yet.
Running NEI in a forge dev environment causes that error on loading a world (clientside). It doesn't really crash so there is no crashlog. Instead the server shuts down normally due to the player being disconnected and the client gets booted to the server selector after a "fatal error" screen. I've cut out the stacktrace from the log and put it on pastebin here.
EDIT: After a couple of crashes I've noticed that the crashes happen when processing mob spawners or when processing mob eggs. It seems to be an even 50/50 chance and I haven't seen the crash happen anywhere else yet.