Add dev dep for es6-error

Author: pluma

package.json

@@ -51,6 +51,7 @@
     "babel-cli": "6.9.0",
     "babel-core": "6.9.1",
     "babel-loader": "6.2.4",
+    "babel-plugin-add-module-exports": "0.2.1",
     "babel-plugin-transform-es2015-modules-commonjs": "6.8.0",
     "babel-preset-es2015": "6.9.0",
     "babel-preset-stage-1": "6.5.0",