fix: update adapter-vercel supported node versions

.changeset/twelve-yaks-travel.md

@@ -0,0 +1,5 @@
+---
+'@sveltejs/adapter-vercel': patch
+---
+
+fix: remove broken node 16 support

documentation/docs/25-build-and-deploy/90-adapter-vercel.md

@@ -50,7 +50,7 @@ export const config = {
 
 The following options apply to all functions:
 
-- `runtime`: `'edge'`, `'nodejs16.x'` or `'nodejs18.x'`. By default, the adapter will select `'nodejs16.x'` or `'nodejs18.x'` depending on the Node version your project is configured to use on the Vercel dashboard
+- `runtime`: `'edge'`, `'nodejs18.x'` or `'nodejs20.x'`. By default, the adapter will select the `'nodejs<version>.x'` corresponding to the Node version your project is configured to use on the Vercel dashboard
 - `regions`: an array of [edge network regions](https://vercel.com/docs/concepts/edge-network/regions) (defaulting to `["iad1"]` for serverless functions) or `'all'` if `runtime` is `edge` (its default). Note that multiple regions for serverless functions are only supported on Enterprise plans
 - `split`: if `true`, causes a route to be deployed as an individual function. If `split` is set to `true` at the adapter level, all routes will be deployed as individual functions
 
@@ -151,7 +151,7 @@ If you have Vercel functions contained in the `api` directory at the project's r
 
 ### Node version
 
-Projects created before a certain date will default to using Node 14, while SvelteKit requires Node 16 or later. You can [change the Node version in your project settings](https://vercel.com/docs/concepts/functions/serverless-functions/runtimes/node-js#node.js-version).
+Projects created before a certain date may default to using an older Node version than what SvelteKit currently requires. You can [change the Node version in your project settings](https://vercel.com/docs/concepts/functions/serverless-functions/runtimes/node-js#node.js-version).
 
 ## Troubleshooting
 

packages/adapter-vercel/index.js

@@ -9,12 +9,11 @@ const DEFAULT_FUNCTION_NAME = 'fn';
 
 const get_default_runtime = () => {
 	const major = process.version.slice(1).split('.')[0];
-	if (major === '16') return 'nodejs16.x';
 	if (major === '18') return 'nodejs18.x';
 	if (major === '20') return 'nodejs20.x';
 
 	throw new Error(
-		`Unsupported Node.js version: ${process.version}. Please use Node 16, Node 18 or Node 20 to build your project, or explicitly specify a runtime in your adapter configuration.`
+		`Unsupported Node.js version: ${process.version}. Please use Node 18 or Node 20 to build your project, or explicitly specify a runtime in your adapter configuration.`
 	);
 };
 
@@ -164,9 +163,9 @@ const plugin = function (defaults = {}) {
 				}
 
 				const node_runtime = /nodejs([0-9]+)\.x/.exec(runtime);
-				if (runtime !== 'edge' && (!node_runtime || node_runtime[1] < 16)) {
+				if (runtime !== 'edge' && (!node_runtime || node_runtime[1] < 18)) {
 					throw new Error(
-						`Invalid runtime '${runtime}' for route ${route.id}. Valid runtimes are 'edge' and 'nodejs16.x' or higher ` +
+						`Invalid runtime '${runtime}' for route ${route.id}. Valid runtimes are 'edge' and 'nodejs18.x' or higher ` +
 							'(see the Node.js Version section in your Vercel project settings for info on the currently supported versions).'
 					);
 				}