fix(server): register OPTIONS fallback middleware at last (#2885)

packages/core/src/server/getDevMiddlewares.ts

@@ -109,16 +109,6 @@ const applyDefaultMiddlewares = async ({
     next();
   });
 
-  middlewares.push((req, res, next) => {
-    if (req.method === 'OPTIONS') {
-      res.statusCode = 200;
-      res.setHeader('Content-Length', '0');
-      res.end();
-      return;
-    }
-    next();
-  });
-
   // dev proxy handler, each proxy has own handler
   if (server.proxy) {
     const { createProxyMiddleware } = await import('./proxy');
@@ -211,6 +201,20 @@ const applyDefaultMiddlewares = async ({
 
   middlewares.push(faviconFallbackMiddleware);
 
+  // OPTIONS request fallback middleware
+  // Should register this middleware as the last
+  // see: https://github.com/web-infra-dev/rsbuild/pull/2867
+  middlewares.push((req, res, next) => {
+    if (req.method === 'OPTIONS') {
+      // Use 204 as no content to send in the response body
+      res.statusCode = 204;
+      res.setHeader('Content-Length', '0');
+      res.end();
+      return;
+    }
+    next();
+  });
+
   return {
     onUpgrade: (...args) => {
       for (const cb of upgradeEvents) {