Use req2params middleware for static map (bbox & center) endpoint

lib/cartodb/controllers/layergroup.js

@@ -71,15 +71,21 @@ LayergroupController.prototype.register = function(app) {
         '/:token/:layer/attributes/:fid', cors(), userMiddleware,
         this.attributes.bind(this));
 
-    app.get(app.base_url_mapconfig +
-        '/static/center/:token/:z/:lat/:lng/:width/:height.:format',
-        cors(), userMiddleware, allowQueryParams(['layer']),
-        this.center.bind(this));
+    app.get(app.base_url_mapconfig + '/static/center/:token/:z/:lat/:lng/:width/:height.:format',
+        cors(),
+        userMiddleware,
+        allowQueryParams(['layer']),
+        this.req2paramsMiddleware,
+        this.center.bind(this)
+    );
 
-    app.get(app.base_url_mapconfig +
-        '/static/bbox/:token/:west,:south,:east,:north/:width/:height.:format',
-        cors(), userMiddleware, allowQueryParams(['layer']),
-        this.bbox.bind(this));
+    app.get(app.base_url_mapconfig + '/static/bbox/:token/:west,:south,:east,:north/:width/:height.:format',
+        cors(),
+        userMiddleware,
+        allowQueryParams(['layer']),
+        this.req2paramsMiddleware,
+        this.bbox.bind(this)
+    );
 
     // Undocumented/non-supported API endpoint methods.
     // Use at your own peril.
@@ -339,17 +345,13 @@ LayergroupController.prototype.center = function(req, res, next) {
 
 LayergroupController.prototype.staticMap = function(req, res, width, height, zoom /* bounds */, center, next) {
     var format = req.params.format === 'jpg' ? 'jpeg' : 'png';
-    req.params.layer = 'all';
-    req.params.format = 'png';
+    req.params.layer = req.params.layer || 'all';
+    req.params.format = req.params.format || 'png';
 
     var self = this;
 
     step(
-        function reqParams() {
-            self.req2params(req, res, this);
-        },
-        function getImage(err) {
-            assert.ifError(err);
+        function getImage() {
             if (center) {
                 self.previewBackend.getImage(
                     new MapStoreMapConfigProvider(self.mapStore, req.context.user, self.userLimitsApi, req.params),