fix: only add handlers for directories that exist

packages/adapter-node/src/handler.js

@@ -1,3 +1,4 @@
+import fs from 'fs';
 import path from 'path';
 import sirv from 'sirv';
 import { fileURLToPath } from 'url';
@@ -14,28 +15,34 @@ const app = new App(manifest);
 
 const __dirname = path.dirname(fileURLToPath(import.meta.url));
 
-const serve_client = sirv(path.join(__dirname, '/client'), {
-	etag: true,
-	maxAge: 31536000,
-	immutable: true,
-	gzip: true,
-	brotli: true
-});
-
-const serve_static = sirv(path.join(__dirname, '/static'), {
-	etag: true,
-	maxAge: 31536000,
-	immutable: true,
-	gzip: true,
-	brotli: true
-});
-
-const serve_prerendered = sirv(path.join(__dirname, '/prerendered'), {
-	etag: true,
-	maxAge: 0,
-	gzip: true,
-	brotli: true
-});
+const paths = {
+	client: path.join(__dirname, '/client'),
+	prerendered: path.join(__dirname, '/prerendered'),
+	static: path.join(__dirname, '/static')
+};
+
+/**
+ * @param {string} path
+ * @param {number} max_age
+ */
+function serve(path, max_age) {
+	return (
+		fs.existsSync(path) &&
+		sirv(path, {
+			etag: true,
+			maxAge: max_age,
+			immutable: true,
+			gzip: true,
+			brotli: true
+		})
+	);
+}
+
+const serve_client = serve(paths.client, 31536000);
+
+const serve_static = serve(paths.static, 31536000);
+
+const serve_prerendered = serve(paths.prerendered, 0);
 
 /** @type {import('polka').Middleware} */
 const ssr = async (req, res) => {
@@ -83,4 +90,6 @@ function sequence(handlers) {
 	};
 }
 
-export const handler = sequence([serve_client, serve_static, serve_prerendered, ssr]);
+export const handler = sequence(
+	[serve_client, serve_static, serve_prerendered, ssr].filter(Boolean)
+);