fix: resolve plugins for proper sorting

packages/astro/src/core/create-vite.ts

@@ -126,30 +126,26 @@ export async function createVite(
 	let result = commonConfig;
 	result = vite.mergeConfig(result, astroConfig.vite || {});
 	result = vite.mergeConfig(result, commandConfig);
-	sortPlugins(result);
 
-	return result;
-}
+	// Resolve plugin config to remove nulls, undefined's, nested arrays, promises,
+	// and anything else Vite supports in the future!
+	const { plugins: resolvedPlugins } = await vite.resolveConfig(result, mode === 'dev' ? 'serve' : 'build');
+	result.plugins = sortPlugins(resolvedPlugins);
 
-function getPluginName(plugin: vite.Plugin) {
-	if (plugin && typeof plugin === 'object' && !Array.isArray(plugin)) {
-		return plugin.name;
-	}
-}
-
-function isVitePlugin(plugin: vite.PluginOption): plugin is vite.Plugin {
-	return Boolean(plugin?.hasOwnProperty('name'))
+	return result;
 }
 
-function sortPlugins(result: ViteConfigWithSSR) {
-	const plugins = result.plugins?.filter(isVitePlugin) ?? []
+function sortPlugins(plugins: readonly vite.Plugin[]): vite.Plugin[] {
+	const result = [...plugins];
 	// HACK: move mdxPlugin to top because it needs to run before internal JSX plugin
 	const mdxPluginIndex =
-		plugins.findIndex((plugin) => getPluginName(plugin) === '@mdx-js/rollup') ?? -1;
-	if (mdxPluginIndex === -1) return;
+		plugins.findIndex((plugin) => plugin.name === '@mdx-js/rollup') ?? -1;
+	if (mdxPluginIndex === -1) return result;
 	const jsxPluginIndex =
-		plugins.findIndex((plugin) => getPluginName(plugin) === 'astro:jsx') ?? -1;
-	const mdxPlugin = result.plugins?.[mdxPluginIndex];
-	result.plugins?.splice(mdxPluginIndex, 1);
-	result.plugins?.splice(jsxPluginIndex, 0, mdxPlugin);
+		plugins.findIndex((plugin) => plugin.name === 'astro:jsx') ?? -1;
+
+	const mdxPlugin = plugins[mdxPluginIndex];
+	result.splice(mdxPluginIndex, 1);
+	result.splice(jsxPluginIndex, 0, mdxPlugin);
+	return result;
 }