Handle 'max waitingClients count exceeded' error as 429 Too many requests

lib/cartodb/api/middlewares/error-middleware.js

@@ -9,7 +9,7 @@ module.exports = function errorMiddleware (/* options */) {
         // jshint maxcomplexity:9
         var allErrors = Array.isArray(err) ? err : [err];
 
-        allErrors = populateTimeoutErrors(allErrors);
+        allErrors = populateLimitErrors(allErrors);
 
         const label = err.label || 'UNKNOWN';
         err = allErrors[0] || new Error(label);
@@ -59,8 +59,21 @@ function getErrorTypes(error) {
     };
 }
 
-function populateTimeoutErrors (errors) {
+function isMaxWaitingClientsError (err) {
+    return err.message === 'max waitingClients count exceeded';
+}
+
+function populateLimitErrors (errors) {
     return errors.map(function (error) {
+        if (isMaxWaitingClientsError(error)) {
+            error.message = 'You are over platform\'s limits: Max render capacity exceeded' +
+                ' Contact CARTO support for more details.';
+            error.type = 'limit';
+            error.http_status = 429;
+
+            return error;
+        }
+
         const errorTypes = getErrorTypes(error);
 
         if (isTimeoutError(errorTypes)) {