diff --git a/development_server.js b/development_server.js
index 1427b3472..797829ef1 100644
--- a/development_server.js
+++ b/development_server.js
@@ -31,6 +31,8 @@ function build() {
       sourceMap: true
     });
     building = false;
+  }, function(err) {
+    console.error(err);
   });
 }