Update rstest/rspack-adapter/rspack.config.ts

Co-authored-by: gemini-code-assist[bot] <176961590+gemini-code-assist[bot]@users.noreply.github.com>

Author: 9aoy

rstest/rspack-adapter/rspack.config.ts

@@ -51,6 +51,6 @@ export default defineConfig({
     new rspack.HtmlRspackPlugin({
       template: './index.html',
     }),
-    isDev ? new ReactRefreshRspackPlugin() : null,
+    ...(isDev ? [new ReactRefreshRspackPlugin()] : []),
   ],
 });