fix(v8/react): From location can be undefined in Tanstack Router Instrumentation (#15237)

backport of #15235 and #15241

---------

Co-authored-by: Tanner Linsley <tannerlinsley@gmail.com>
Co-authored-by: Francesco Novy <francesco.novy@sentry.io>

Author: 3 people

packages/react/src/tanstackrouter.ts

@@ -64,8 +64,9 @@ export function tanstackRouterBrowserTracingIntegration(
       if (instrumentNavigation) {
         // The onBeforeNavigate hook is called at the very beginning of a navigation and is only called once per navigation, even when the user is redirected
         castRouterInstance.subscribe('onBeforeNavigate', onBeforeNavigateArgs => {
+          const fromLocationState = onBeforeNavigateArgs.fromLocation && onBeforeNavigateArgs.fromLocation.state;
           // onBeforeNavigate is called during pageloads. We can avoid creating navigation spans by comparing the states of the to and from arguments.
-          if (onBeforeNavigateArgs.toLocation.state === onBeforeNavigateArgs.fromLocation.state) {
+          if (onBeforeNavigateArgs.toLocation.state === fromLocationState) {
             return;
           }
 

packages/react/src/vendor/tanstackrouter-types.ts

@@ -46,7 +46,7 @@ export interface VendoredTanstackRouter {
     eventType: 'onResolved' | 'onBeforeNavigate',
     callback: (stateUpdate: {
       toLocation: VendoredTanstackRouterLocation;
-      fromLocation: VendoredTanstackRouterLocation;
+      fromLocation?: VendoredTanstackRouterLocation;
     }) => void,
   ): () => void;
 }