Can't catch exception for invalid input about dnscache

[timbowhite]

+1

[timbowhite]

OK the issue is that you can't catch the errors because dnscache wraps the original method with their own callback. So a fix could be for dnscache to try/catch in it's wrapper callback, then call the user callback with an error on catch, ie:

        // override dns.reverse method
        dns.reverse = function (ip, callback) {
            cache.get('reverse_' + ip, function (error, record) {
                if (record) {
                    callback(error, deepCopy(record));
                } else {
                    try{
                        backup_object.reverse(ip, function (err, addresses) {
                            if (err) {
                                callback(err);
                            } else {
                                cache.set('reverse_' + ip, addresses, function () {
                                    callback(err, deepCopy(addresses));
                                });
                            }
                        });
                    }
                    catch(err){
                        callback(err);
                    }
                }
            });
        };

The above change will give you an error in your callback, but won't throw. It's an easy fix, I'll send in a PR.