Avoid functions with side effects

lib/cartodb/models/mapconfig/provider/named-map-provider.js

@@ -57,7 +57,6 @@ NamedMapMapConfigProvider.prototype.getMapConfig = function(callback) {
     }
 
     var mapConfig = null;
-    var rendererParams;
     var apiKey;
 
     var context = {};
@@ -68,11 +67,7 @@ NamedMapMapConfigProvider.prototype.getMapConfig = function(callback) {
             return callback(err);
         }
 
-        rendererParams = _.extend({}, this.params, {
-            user: this.owner
-        });
-
-        this.setDBParams(this.owner, rendererParams, (err) => {
+        this.getDBParams(this.owner, (err, rendererParams) => {
             if (err) {
                 this.err = err;
                 return callback(err);
@@ -253,19 +248,23 @@ function configHash(config) {
 
 module.exports.configHash = configHash;
 
-NamedMapMapConfigProvider.prototype.setDBParams = function(cdbuser, params, callback) {
+NamedMapMapConfigProvider.prototype.getDBParams = function(cdbuser, callback) {
+    const dbParams = _.extend({}, this.params, {
+        user: this.owner
+    });
+
     this.pgConnection.getDatabaseParams(cdbuser, (err, databaseParams) => {
         if (err) {
             return callback(err);
         }
 
-        params.dbuser = databaseParams.dbuser;
-        params.dbpass = databaseParams.dbpass;
-        params.dbhost = databaseParams.dbhost;
-        params.dbport = databaseParams.dbport;
-        params.dbname = databaseParams.dbname;
+        dbParams.dbuser = databaseParams.dbuser;
+        dbParams.dbpass = databaseParams.dbpass;
+        dbParams.dbhost = databaseParams.dbhost;
+        dbParams.dbport = databaseParams.dbport;
+        dbParams.dbname = databaseParams.dbname;
 
-        callback();
+        return callback(null, dbParams);
     });
 };