Fix webpack warning require.extensions is not supported by webpack. Use a loader instead.

Signed-off-by: Hung-Han (Henry) Chen <1474479+chenhunghan@users.noreply.github.com>

webpack.extensions.ts

@@ -101,7 +101,14 @@ export default function (): webpack.Configuration {
       ]
     },
     resolve: {
-      extensions: [".ts", ".tsx", ".js"]
+      extensions: [".ts", ".tsx", ".js"],
+      // the alias is to avoid webpack warning
+      // "require.extensions is not supported by webpack. Use a loader instead."
+      // from ./src/extensions/cluster-feature.ts
+      // the trick is from <https://github.com/handlebars-lang/handlebars.js/issues/953#issuecomment-239874313>
+      alias: {
+        "handlebars": "handlebars/dist/handlebars.js"
+      }
     },
     plugins: [
       // In ts-loader's README they said to output a built .d.ts file,