I can reproduce the bug, and got it in gdb with debug symbols.

I'm running:
GNU Emacs 23.1.1 (x86_64-pc-linux-gnu, X toolkit, Xaw3d scroll bars) of 2010-03-26 on crested, modified by Debian

Attached is the 'bt full' output from the SEGV after 'emacs --batch -l json-crash.el'