fix: self mount error

src/app.ts

@@ -135,9 +135,12 @@ export class FreshApp<State> implements App<State> {
     // - `app.mounApp("*", otherApp)`
     const isSelf = path === "*" || path === "/";
     if (isSelf) {
-      const first = this._router._routes[0];
-      if (first.method === "ALL" && first.path === "*") {
-        first.handlers.push(...middlewares);
+      const selfRoutes = this._router._routes;
+      if (
+        selfRoutes.length > 0 && selfRoutes[0].method === "ALL" &&
+        selfRoutes[0].path === "*"
+      ) {
+        selfRoutes[0].handlers.push(...middlewares);
       } else {
         this._router._routes.unshift({
           handlers: middlewares,

src/app_test.ts

@@ -316,3 +316,20 @@ Deno.test(
     expect(await res.text()).toEqual("AB");
   },
 );
+
+Deno.test("FreshApp - .mountApp() self mount empty", async () => {
+  const innerApp = new FreshApp<{ text: string }>()
+    .use((ctx) => {
+      ctx.state.text = "A";
+      return ctx.next();
+    })
+    .get("/foo", (ctx) => new Response(ctx.state.text));
+
+  const app = new FreshApp<{ text: string }>()
+    .mountApp("/", innerApp);
+
+  const server = new FakeServer(await app.handler());
+
+  const res = await server.get("/foo");
+  expect(await res.text()).toEqual("A");
+});