Fix log of errors not rendering the error message/data in the JSON renderer.

lib/renderers/JsonRenderer.js

@@ -13,8 +13,16 @@ JsonRenderer.prototype.end = function (data) {
 };
 
 JsonRenderer.prototype.error = function (err) {
+    var message = err.message;
+
     err.id = err.code || 'error';
     err.level = 'error';
+    err.data = err.data || {};
+
+    // Need to set message again because it is
+    // not enumerable in some cases
+    delete err.message;
+    err.message = message;
 
     this.log(err);
     this.end();