fix(router-core): treat null return from beforeLoad as no-op for route context

.changeset/fix-beforeload-null-context.md

@@ -0,0 +1,9 @@
+---
+'@tanstack/router-core': patch
+---
+
+fix(router-core): treat null return from beforeLoad as no-op for route context
+
+When `beforeLoad` returns `null`, it is now treated the same as `undefined` (no-op) instead of being stored as `__beforeLoadContext: null`. This is consistent with how the `context` route option already handles null returns via `?? undefined`, and prevents null from silently interfering with context accumulation.
+
+Fixes #7110

packages/react-router/tests/routeContext.test.tsx

@@ -2630,6 +2630,42 @@ describe('useRouteContext in the component', () => {
     expect(content).toBeInTheDocument()
   })
 
+  test('route context preserved when beforeLoad returns null', async () => {
+    const rootRoute = createRootRoute({
+      beforeLoad: () => null,
+      component: () => {
+        const context = rootRoute.useRouteContext()
+        return <div>{JSON.stringify(context)}</div>
+      },
+    })
+    const routeTree = rootRoute.addChildren([])
+    const router = createRouter({ routeTree, history, context: { foo: 'bar' } })
+
+    render(<RouterProvider router={router} />)
+
+    const content = await screen.findByText(JSON.stringify({ foo: 'bar' }))
+
+    expect(content).toBeInTheDocument()
+  })
+
+  test('route context preserved when async beforeLoad returns null', async () => {
+    const rootRoute = createRootRoute({
+      beforeLoad: async () => null,
+      component: () => {
+        const context = rootRoute.useRouteContext()
+        return <div>{JSON.stringify(context)}</div>
+      },
+    })
+    const routeTree = rootRoute.addChildren([])
+    const router = createRouter({ routeTree, history, context: { foo: 'bar' } })
+
+    render(<RouterProvider router={router} />)
+
+    const content = await screen.findByText(JSON.stringify({ foo: 'bar' }))
+
+    expect(content).toBeInTheDocument()
+  })
+
   test('route context (sleep in beforeLoad), present in the root route', async () => {
     const rootRoute = createRootRoute({
       beforeLoad: async () => {

packages/router-core/src/load-matches.ts

@@ -490,7 +490,7 @@ const executeBeforeLoad = (
   }
 
   const updateContext = (beforeLoadContext: any) => {
-    if (beforeLoadContext === undefined) {
+    if (beforeLoadContext === undefined || beforeLoadContext === null) {
       inner.router.batch(() => {
         pending()
         resolve()