fix(singlefetch): handle root path with basename

Author: ThisIsAreku

.changeset/itchy-chefs-give.md

@@ -0,0 +1,6 @@
+---
+"@remix-run/react": patch
+"@remix-run/server-runtime": patch
+---
+
+fix(singlefetch): handle root path with basename

contributors.yml

@@ -662,6 +662,7 @@
 - tascord
 - TheRealAstoo
 - therealflyingcoder
+- ThisIsAreku
 - thomasheyenbrock
 - thomasrettig
 - thomasverleye

packages/remix-react/single-fetch.tsx

@@ -393,6 +393,8 @@ export function singleFetchUrl(reqUrl: URL | string) {
 
   if (url.pathname === "/") {
     url.pathname = "_root.data";
+  } else if (url.pathname === window.__remixContext.basename) {
+    url.pathname = window.__remixContext.basename.concat("_root.data");
   } else {
     url.pathname = `${url.pathname.replace(/\/$/, "")}.data`;
   }

packages/remix-server-runtime/server.ts

@@ -195,7 +195,7 @@ export const createRequestHandler: CreateRequestHandlerFunction = (
       let handlerUrl = new URL(request.url);
       handlerUrl.pathname = handlerUrl.pathname
         .replace(/\.data$/, "")
-        .replace(/^\/_root$/, "/");
+        .replace(_build.basename ? /\/_root$/ : /^\/_root$/, "/");
 
       let singleFetchMatches = matchServerRoutes(
         routes,