fix error catching

Author: s0ph1e

lib/load.js

@@ -331,12 +331,12 @@ var Loader = function (data) {
       }
 
       process()
-        .then(function (res, e) {
-          if (e) {
-            errorCleanup();
-            res = null;
-          }
-          return callback(e, res);
+        .then(function (res) {
+          return callback(null, res);
+        })
+        .catch(function (e) {
+          errorCleanup();
+          return callback(e);
         });
     }
   }