Here is the backtrace:
----------------------

(gdb) xbacktrace 
0x83a4b24 "ychat-bineq"
0x83a518c "ychat-search-delimeter"
0x83a4e98 "ychat-parse-speech"
0x83a4bd8 "ychat-direct-incoming-packet"
0x83a4b3c "ychat-parse-header"
0x83a4a90 "ychat-get-packet"
0x83bf898 "ychat-insertion-filter"

And here is the function it's dying in:
---------------------------------------

(defun ychat-bineq (buf int &optional offset)
  "Internal function.  Compares int to the byte at (point).  If offset
is set, compare to (+ (point) 1)."
  (let ((off (or offset
		 0)))
    (with-current-buffer buf
      (if (and (<= 2 (string-bytes (buffer-substring (+ (point) off)
						     (point-max))))
	       (= int (ychat-bin-int (concat (ychat-hex-bin "00")
					     (buffer-substring (+ (point) off)
							       (+ (point) off 1))))))
	  (setq ret t)
	(setq ret nil))))
  ret)

(defun ychat-hex-bin (hex)
  "Return a binary string from a hex string HEX.
It ignores all non-lower letter hex characters, which makes reading string
from `eicq-bin-pretty-hex' and netwrok debug convenient.  If the length of
HEX is odd, ?0 is appended to its end."
  (interactive "sHex: ")
  (setq hex (downcase hex))
  ;; stole from hexl.el
  (while (string-match "[^a-f0-9]" hex)
    (setq hex (replace-match "" t t hex)))

  (let (hex-list high low bin)
    (setq hex-list
          (mapcar
           (lambda (x)
             (if (and (>= x ?0) (<= x ?9))
                 (- x ?0) (+ 10 (- x ?a))))
           hex))
    (while hex-list
      (setq high (pop hex-list))
      (setq low (or (pop hex-list) 0))
      (setq bin (concat bin (char-to-string
                             (+ (* high 16) low)))))
    (if (interactive-p) (kill-new bin))
    bin))