I confirm, I got the same problem in ERC.

Here's the backtrace:
(gdb) bt
#0  0x00000000005cabf6 in find_automatic_composition (pos=13, limit=13, start=0x7fffffffdd58, end=0x7fffffffdd60, gstring=0x7fffffffdd68, string=11901442) at composite.c:1607
#1  0x00000000005cf7af in composition_adjust_point (last_pt=13, new_pt=13) at composite.c:1709
#2  0x000000000050f19b in command_loop_1 () at keyboard.c:1673
#3  0x0000000000572743 in internal_condition_case (bfun=0x50e0c0 <command_loop_1>, handlers=11953826, hfun=0x502ec0 <cmd_error>) at eval.c:1507
#4  0x000000000050144e in command_loop_2 (ignore=<value optimized out>) at keyboard.c:1156
#5  0x0000000000572618 in internal_catch (tag=12164544, func=0x501430 <command_loop_2>, arg=11901442) at eval.c:1261
#6  0x000000000050299f in command_loop () at keyboard.c:1135
#7  recursive_edit_1 () at keyboard.c:756
#8  0x0000000000502cd7 in Frecursive_edit () at keyboard.c:820
#9  0x000000000041697d in main (argc=1, argv=<value optimized out>) at emacs.c:1686

-- 
Julien Danjou
❱ http://julien.danjou.info