fix: fastify server should return 404 response
diff --git a/packages/dubbo-fastify/src/fastify-dubbo-plugin.ts b/packages/dubbo-fastify/src/fastify-dubbo-plugin.ts
index 855517b..3f9fd51 100644
--- a/packages/dubbo-fastify/src/fastify-dubbo-plugin.ts
+++ b/packages/dubbo-fastify/src/fastify-dubbo-plugin.ts
@@ -92,7 +92,10 @@
       {},
       async function handleFastifyRequest(req, reply) {
         const uHandler = handlersMap.get((req.headers['tri-service-version'] ?? "") as string + (req.headers['tri-service-group'] ?? "") as string);
-        if(!uHandler) return;
+        if(!uHandler) {
+          reply.status(404).send({ status: Code.Unimplemented, message: 'HTTP 404' });
+          return;
+        }
         try {
           const uRes = await uHandler(
             universalRequestFromNodeRequest(