$ emacs --version GNU Emacs 23.1.50.1
Warning (slime): "s-code.lisp":921:4 (pt=35805). Caught error when trying to extend the region for fontification. The error was: (cl-assertion-failed (not (plusp (nth 0 (slime-current-parser-state))))) Further: font-lock-beg=35981, font-lock-end=36491.
Backtrace: backtrace() slime-bug("Caught error when trying to extend the region for fontification. The error was: %S Further: font-lock-beg=%d, font-lock-end=%d." (cl-assertion-failed (not (plusp ...))) 35981 36491) slime-extend-region-for-font-lock() font-lock-default-fontify-region(35981 36491 nil) font-lock-fontify-region(35981 36491) run-hook-with-args(font-lock-fontify-region 35981 36491) byte-code("\302\303 #\207" [start next run-hook-with-args jit-lock-functions] 4) jit-lock-fontify-now(35981 36481) jit-lock-function(35981)