Use runtime babel helpers

template/default/package.json

@@ -21,14 +21,16 @@
     "predeploy": "cd example && {{manager}} install && {{manager}} run build",
     "deploy": "gh-pages -d example/build"
   },
+  "dependencies": {
+    "@babel/runtime": "^7.0.0"
+  },
   "peerDependencies": {
     "prop-types": "^15.5.4",
     "react": "^15.0.0 || ^16.0.0",
     "react-dom": "^15.0.0 || ^16.0.0"
   },
   "devDependencies": {
     "@babel/core": "^7.0.0",
-    "@babel/plugin-external-helpers": "^7.0.0",
     "@babel/plugin-proposal-class-properties": "^7.0.0",
     "@babel/plugin-proposal-decorators": "^7.0.0",
     "@babel/plugin-proposal-do-expressions": "^7.0.0",

template/default/rollup.config.js

@@ -8,32 +8,38 @@ import svgr from '@svgr/rollup'
 
 import pkg from './package.json'
 
-export default {
+const createConfig = ({ output }) => ({
   input: 'src/index.js',
-  output: [
-    {
-      file: pkg.main,
-      format: 'cjs',
-      sourcemap: true
-    },
-    {
-      file: pkg.module,
-      format: 'es',
-      sourcemap: true
-    }
-  ],
+  output: Object.assign({ sourcemap: true }, output),
   plugins: [
-    external(),
+    external({ includeDependencies: true }),
     postcss({
       modules: true
     }),
     url(),
     svgr(),
     babel({
       exclude: 'node_modules/**',
-      plugins: [ '@babel/external-helpers' ]
+      runtimeHelpers: true,
+      plugins: [
+        [
+          '@babel/transform-runtime',
+          { useESModules: output.format !== 'cjs' }
+        ]
+      ]
     }),
     resolve(),
     commonjs()
   ]
-}
+})
+
+export default [
+  createConfig({
+    file: pkg.main,
+    format: 'cjs',
+  }),
+  createConfig({
+    file: pkg.module,
+    format: 'esm',
+  })
+]