fix: Fix navigate bug from nested index routes (#8965)

Author: brophdawg11

packages/react-router/__tests__/navigate-test.tsx

@@ -192,5 +192,30 @@ describe("<Navigate>", () => {
         </h1>
       `);
     });
+
+    it("handles relative navigation from nested index route", () => {
+      let renderer: TestRenderer.ReactTestRenderer;
+      TestRenderer.act(() => {
+        renderer = TestRenderer.create(
+          <MemoryRouter initialEntries={["/layout/thing"]}>
+            <Routes>
+              <Route path="layout">
+                <Route path=":param">
+                  {/* redirect /layout/:param/ index routes to /layout/:param/dest */}
+                  <Route index element={<Navigate to="dest" />} />
+                  <Route path="dest" element={<h1>Destination</h1>} />
+                </Route>
+              </Route>
+            </Routes>
+          </MemoryRouter>
+        );
+      });
+
+      expect(renderer.toJSON()).toMatchInlineSnapshot(`
+        <h1>
+          Destination
+        </h1>
+      `);
+    });
   });
 });

packages/react-router/lib/hooks.tsx

@@ -155,16 +155,14 @@ export function useNavigate(): NavigateFunction {
   let { matches } = React.useContext(RouteContext);
   let { pathname: locationPathname } = useLocation();
 
-  // Ignore pathless matches (i.e., share the same pathname as their ancestor)
+  // Ignore index + pathless matches
   let pathContributingMatches = matches.filter(
     (match, index) =>
-      index === 0 || match.pathnameBase !== matches[index - 1].pathnameBase
+      index === 0 ||
+      (!match.route.index &&
+        match.pathnameBase !== matches[index - 1].pathnameBase)
   );
 
-  if (matches.length > 0 && matches[matches.length - 1].route.index) {
-    pathContributingMatches.pop();
-  }
-
   let routePathnamesJson = JSON.stringify(
     pathContributingMatches.map((match) => match.pathnameBase)
   );