I have managed to find the cause of the (debugger-info-for-emacs) failing. In documentation it is said: (debugger-info-for-emacs) returns a list (condition-description ...)
condition-description---a string describing the condition that triggered the debugger.
yet debugger-condition-for-emacs -
(defun debugger-condition-for-emacs () (list (safe-condition-message *swank-debugger-condition*) (format nil " [Condition of type ~S]" (type-of *swank-debugger-condition*))))
the function generating condition-description returns a list of two strings ... so it is pretty strange that I was the only one to encounter this problem ... Ignas Mikalajunas