fix: only for lib mode and es format

Author: wxsms

README.md

@@ -30,4 +30,4 @@ export default defineConfig({
 });
 ```
 
-Note that this plugin can only work with [library-mode](https://vitejs.dev/guide/build.html#library-mode).
+Note that this plugin will only work with [library-mode](https://vitejs.dev/guide/build.html#library-mode) and es format build.

index.js

@@ -8,17 +8,29 @@ module.exports = function () {
     name: 'lib-css',
     apply: 'build',
     enforce: 'post',
+
     configResolved (resolvedConfig) {
       viteConfig = resolvedConfig;
     },
-    writeBundle (_, bundle) {
+
+    writeBundle (option, bundle) {
+      if (!viteConfig.build || !viteConfig.build.lib) {
+        // only for lib build
+        console.warn('vite-plugin-libcss only works in lib mode.')
+        return;
+      }
+      if (option.format !== 'es') {
+        // only for es built
+        return;
+      }
       const files = Object.keys(bundle);
       const cssFile = files.find((v) => v.endsWith('.css'));
       if (!cssFile) {
         return;
       }
       for (const file of files) {
-        if (!file.endsWith('.js')) {
+        if (!bundle[file].isEntry) {
+          // only for entry
           continue;
         }
         const outDir = viteConfig.build.outDir || 'dist';