Added logic for when an error doesn't have an `code` property.

lib/dialects/mysql/connection-manager.js

@@ -41,6 +41,7 @@ ConnectionManager.prototype.connect = function(config) {
 
     connection.connect(function(err) {
       if (err) {
+        if (err.code) {
           switch (err.code) {
           case 'ECONNREFUSED':
             reject(new sequelizeErrors.ConnectionRefusedError(err));
@@ -61,6 +62,9 @@ ConnectionManager.prototype.connect = function(config) {
             reject(new sequelizeErrors.ConnectionError(err));
             break;
           }
+        } else {
+          reject(new sequelizeErrors.ConnectionError(err));
+        }
 
         return;
       }