So siehts ganz gut aus !

node_modules/babel-runtime/helpers/temporalRef.js

@@ -0,0 +1,11 @@
+"use strict";
+
+exports.__esModule = true;
+
+exports.default = function (val, name, undef) {
+  if (val === undef) {
+    throw new ReferenceError(name + " is not defined - temporal dead zone");
+  } else {
+    return val;
+  }
+};