sub _scalar_to_string
{
    my $s = shift;

    return 'null' unless defined $s;

    if (ref $s) # object other than plain HASH, ARRAY, or SCALAR?
    {
        #... (this is something JSON doesn't handle)
    }
    elsif (looks_like_number($s))
    {
        return $s
    }
    else
    {
        eval {
            $s = "" . $s;
            $s =~ s[\\][\\\\]g; ### error points here
            $s =~ s["][\\"]g;
            $s =~ s[\n][\\n]g;
            $s =~ s[[\b]][\\b]g;
            $s =~ s[\f][\\f]g;
            $s =~ s[\r][\\r]g;
            $s =~ s[\t][\\t]g;
            $s =~ s[([^[:print:]])][sprintf "\\u%04x", ord $1]eg;
            1;
        } and return qq["$s"];
        return qq[":$@:$s"];
    }
}