Prevent duplicate children in addResolvedRoutesToParent

Author: onurtemizkan

dev-packages/e2e-tests/test-applications/react-router-7-lazy-routes/tests/transactions.test.ts

@@ -4,8 +4,6 @@ import { waitForTransaction } from '@sentry-internal/test-utils';
 
 test('Creates a pageload transaction with parameterized route', async ({ page }) => {
   const transactionPromise = waitForTransaction('react-router-7-lazy-routes', async transactionEvent => {
-    console.debug('transactionEvent', transactionEvent);
-
     return (
       !!transactionEvent?.transaction &&
       transactionEvent.contexts?.trace?.op === 'pageload' &&

packages/react/src/reactrouterv6-compat-utils.tsx

@@ -66,11 +66,22 @@ const allRoutes = new Set<RouteObject>();
 
 /**
  * Adds resolved routes as children to the parent route.
+ * Prevents duplicate routes by checking if they already exist.
  */
 function addResolvedRoutesToParent(resolvedRoutes: RouteObject[], parentRoute: RouteObject): void {
-  parentRoute.children = Array.isArray(parentRoute.children)
-    ? [...parentRoute.children, ...resolvedRoutes]
-    : resolvedRoutes;
+  const existingChildren = parentRoute.children || [];
+  
+  const newRoutes = resolvedRoutes.filter(newRoute => 
+    !existingChildren.some(existing => 
+      existing === newRoute || 
+      (newRoute.path && existing.path === newRoute.path) ||
+      (newRoute.id && existing.id === newRoute.id)
+    )
+  );
+
+  if (newRoutes.length > 0) {
+    parentRoute.children = [...existingChildren, ...newRoutes];
+  }
 }
 
 /**