*error*
(*error* string)
The *error* function is used to handle errors. A redefinition of this built-in function lets you implement application-specific error handling.
For example, you can make sure that certain system variables are reset if a function is cancelled by the user or an error occurs in your function.
The argument to the function is a string that retrieves the error message passed to the function by the Lisp interpreter.
The built-in routine for error handling is restored by executing the expression:
(setq *error* nil)
(defun *error* (msg)
(princ "Error: ")
(princ msg)
(princ)
)