General Error-Signalling Functions

CLtL2 Reference 

If *error-abort-handler* is non-nil, then an ABORT option is available inside ERROR and CERROR.
If chosen, then the handler is funcalled on no arguments. 

variable *ERROR-HANDLER*
If *ERROR-SIGNAL* is non-nil, then that function is called upon an error. Otherwise, the debugger is invoked. 

variable *ERROR-MESSAGE* 

function ERROR : (format-string &rest arguments) 

variable *CONTINUE-CERROR?* 

function CERROR : (continue-string format-string &rest arguments) 

variable *IGNORE-WARNS?*
If T, all warnings forms are ignored 

function WARN : (format-string &rest arguments) 

variable *IGNORE-BREAKS?*
If non-NIL, all break forms are ignored 

function BREAK : (format-string &rest arguments)