@lisp
;;; If the first user-processable command-line argument is a filename,
;;; disable the debugger, load the file handling shebang-line and quit.
-(let ((script (probe-file (second sb-ext:*posix-argv*))))
+(let ((script (and (second sb-ext:*posix-argv*)
+ (probe-file (second sb-ext:*posix-argv*)))))
(when script
;; Handle the possible shebang-line
(set-dispatch-macro-character #\# #\!