invoke-debugger condition =>|
condition---a condition object.
invoke-debugger attempts to enter the debugger with condition.
If *debugger-hook* is not nil, it should be a function (or the name of a function) to be called prior to entry to the standard debugger. The function is called with *debugger-hook* bound to nil, and the function must accept two arguments: the condition and the value of *debugger-hook* prior to binding it to nil. If the function returns normally, the standard debugger is entered.
The standard debugger never directly returns. Return can occur only by a non-local transfer of control, such as the use of a restart function.
(ignore-errors ;Normally, this would suppress debugger entry (handler-bind ((error #'invoke-debugger)) ;But this forces debugger entry (error "Foo."))) Debug: Foo. To continue, type :CONTINUE followed by an option number: 1: Return to Lisp Toplevel. Debug>
*debugger-hook* is bound to nil, program execution is discontinued, and the debugger is entered.
*debug-io* and *debugger-hook*.