What's wrong with just dying in AUTOLOAD?

sub AUTOLOAD {
    (my $meth = our $AUTOLOAD) =~ s/([^:]+)$/$1/;

    if ( $meth =~ /^is_/ ) {
        return;
    } else {
        die "No such subroutine '$meth''";
   }
}
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It's not exactly the same as you want, though (but it also happens at runtime).