Merge index.js (#34963)

Fix #34960

templates/base/head_script.tmpl

@@ -46,4 +46,4 @@ If you introduce mistakes in it, Gitea JavaScript code wouldn't run correctly.
 	{{/* in case some pages don't render the pageData, we make sure it is an object to prevent null access */}}
 	window.config.pageData = window.config.pageData || {};
 </script>
-<script src="{{AssetUrlPrefix}}/js/webcomponents.js?v={{AssetVersion}}"></script>
+<script src="{{AssetUrlPrefix}}/js/index.js?v={{AssetVersion}}" onerror="alert('Failed to load asset files from ' + this.src + '. Please make sure the asset files can be accessed.')"></script>