Make the error flag more strict

lib/carto/renderer_js.js

@@ -239,11 +239,12 @@ CartoCSS.prototype = {
       for(var i = 0; i < defs.length; ++i) {
         var def = defs[i];
 
+        if (this.options.strict) {
           def.toXML(parse_env, {});
-
+          if (parse_env.errors.message) {
-        if (this.options.strict && parse_env.errors.message) {
             throw new Error(parse_env.errors.message);
           }
+        }
 
         var k = defKey(def);
         var layer = layers[k];