You can raise exceptions from your own code using the built-in predicate
The argument to this predicate is the exception code; it is an arbitrary non-variable term of which the principal functor indicates the exception class. You can use the same exception classes as the system (see ref-ere-err), or you can use your own exception classes.
Error messages like the one shown above are printed using the built-in
print_message/2. One of the arguments to
the exception code.
print_message can be extended, as described in
ref-msg, so that you can have appropriate error messages
printed corresponding to your own exception classes.