Fix webpack HMR

assets/build/util/assetsPluginProcessOutput.js

@@ -0,0 +1,18 @@
+const path = require('path');
+
+/**
+ * Process AssetsPlugin output and format it
+ * for Sage: {"[name].[ext]":"[name]_[hash].[ext]"}
+ * @param  {Object} assets passed by processOutput
+ * @return {String}        JSON
+ */
+module.exports = (assets) => {
+  const results = {};
+  Object.keys(assets).forEach(name => {
+    Object.keys(assets[name]).forEach(ext => {
+      const filename = `${path.dirname(assets[name][ext])}/${path.basename(`${name}.${ext}`)}`;
+      results[filename] = assets[name][ext];
+    });
+  });
+  return JSON.stringify(results);
+};