The simple, reliable and useful specification is to state that such a
failure raises an exception, the implementation is required to produce
a suitable diagnostic and take appropriate action (which might involve
termination). Vague, yes, but it makes the intent clear. That option
is for locating errors.
Even the notion of termination is vague, when you have things like
programs calling other programs (see for instance shell scripts
and the notion of subshell, sometimes spawn in an implicit way),
compilation from within the program (like Perl's eval), plugins,
and so on.