feat: support serverMiddleware (#26)

src/index.ts

@@ -32,19 +32,26 @@ export default <Module> function slsModule () {
   // TODO: render:setupMiddleware hook
   // TODO: support m.prefix and m.route
   nuxt.hook('modules:done', () => {
+    const unsupported = []
     for (let m of nuxt.options.serverMiddleware) {
       if (typeof m === 'string') {
         m = { handler: m }
       }
-      if (typeof m.handler !== 'string') {
-        console.warn('[Serverless] Unsupported serverMiddleware format:', m)
-        continue
-      }
 
       const route = m.path || m.route || '/'
       const handle = nuxt.resolver.resolvePath(m.handler || m.handle)
+
+      if (typeof handle !== 'string' || typeof route !== 'string') {
+        unsupported.push(m)
+        continue
+      }
+
       options.serverMiddleware.push({ route, handle })
     }
+    if (unsupported.length) {
+      console.warn('[serverless] Unsupported Server middleware used: ', unsupported)
+      console.info('Supported format is `{ path: string, handler: string }` and handler should export `(req, res) => {}`')
+    }
   })
 
   if (options.nuxtHooks) {