fix(connection): set readyState to disconnected if initial connection fails

Fix #6244

Author: vkarpov15

lib/connection.js

@@ -337,6 +337,7 @@ Connection.prototype.openUri = function(uri, options, callback) {
   const promise = new Promise((resolve, reject) => {
     parser(uri, options, (error, parsed) => {
       if (error) {
+        this.readyState = STATES.disconnected;
         if (_this.listeners('error').length > 0) {
           _this.emit('error', error);
         }
@@ -357,6 +358,7 @@ Connection.prototype.openUri = function(uri, options, callback) {
 
       mongodb.MongoClient.connect(uri, options, function(error, client) {
         if (error) {
+          _this.readyState = STATES.disconnected;
           if (_this.listeners('error').length > 0) {
             _this.emit('error', error);
           }
@@ -366,13 +368,6 @@ Connection.prototype.openUri = function(uri, options, callback) {
         _this.db = db;
         _this.client = client;
 
-        if (error) {
-          _this.readyState = STATES.disconnected;
-          if (_this.listeners('error').length) {
-            _this.emit('error', error);
-          }
-          return reject(error);
-        }
         // Backwards compat for mongoose 4.x
         db.on('reconnect', function() {
           _this.readyState = STATES.connected;