Index: frontend/node_modules/promise/polyfill-done.js
===================================================================
--- frontend/node_modules/promise/polyfill-done.js	(revision 9af201e94b5a79beb92a30858fc54de4bc3b9449)
+++ frontend/node_modules/promise/polyfill-done.js	(revision 9af201e94b5a79beb92a30858fc54de4bc3b9449)
@@ -0,0 +1,12 @@
+// should work in any browser without browserify
+
+if (typeof Promise.prototype.done !== 'function') {
+  Promise.prototype.done = function (onFulfilled, onRejected) {
+    var self = arguments.length ? this.then.apply(this, arguments) : this
+    self.then(null, function (err) {
+      setTimeout(function () {
+        throw err
+      }, 0)
+    })
+  }
+}