&restargs → implementation-dependent
The function invalid-method-error is used to signal an error of type error when there is an applicable method whose qualifiers are not valid for the method combination type. The error message is constructed by using the format-control suitable for format and any args to it. Because an implementation may need to add additional contextual information to the error message, invalid-method-error should be called only within the dynamic extent of a method combination function.
The function invalid-method-error is called automatically when a method fails to satisfy every qualifier pattern and predicate in a define-method-combination form. A method combination function that imposes additional restrictions should call invalid-method-error explicitly if it encounters a method it cannot accept.
The debugger might be entered.