Little refactor

app.js

function handlePossibleError(err) {
  if (!err) return;
  console.log('------- ERROR --------');
  console.error(err);
  console.log('----------------------');
}

function insertIntoDatabase(db, data) {
  var tweets = db.collection('tweets');
  var reg = /(https:\/\/.+)/g;
  var textArray = res.text.split(reg);

  tweets.insert({
    'saved_by': data.tweet.user.id_str,
    'saved_by_name': data.tweet.user.name,
    'saved_by_screenname': data.tweet.user.screen_name,
    'text': textArray[0],
    'link': textArray[1],
    'user_id': data.userId,
    'user_name': data.userName
  });

  db.close(handlePossibleError);
}

twitter.stream("statuses/filter", {track: "@twtsvr"}, function (stream) {
  stream.on("data", function (tweet) {
    if (tweet.in_reply_to_status_id && /savethis!/i.test(tweet.text)) {
        twitter.get(apiUrl + tweet.in_reply_to_status_id_str, function (req, res) {
          mongo.MongoClient.connect(mongoUri, function (err, db) {
            if (!err) {
              return insertIntoDatabase(db, { tweet: tweet, userId: res.user.id_str, userName: res.user.name });
            }
            handlePossibleError(err);
          });
        });
      };
  });

  stream.on("error", handlePossibleError);
});