Skip null values for quantification methods generating null values

lib/cartodb/backends/turbo-carto-postgres-datasource.js

@@ -84,6 +84,10 @@ PostgresDatasource.prototype.getRamp = function (column, buckets, method, callba
 
         var strategy = method2strategy[methodName];
         var ramp = result[0][methodName] || [];
+        // Skip null values from ramp
+        // Generated turbo-carto won't be correct, but better to keep it working than failing
+        // TODO fix cartodb-postgres extension quantification functions
+        ramp = ramp.filter(function(value) { return value !== null; });
         if (strategy !== STRATEGY.EXACT) {
             ramp = ramp.sort(function(a, b) {
                 return a - b;