fix client test

Author: iker-barriocanal

packages/nextjs/src/performance/client.ts

@@ -2,7 +2,8 @@
 
 import { Primitive, Transaction, TransactionContext } from '@sentry/types';
 import { fill, getGlobalObject, stripUrlQueryAndFragment } from '@sentry/utils';
-import { default as Router } from 'next/router';
+
+import { Router } from '../../src/utils/nextImporter';
 
 const global = getGlobalObject<Window>();
 

packages/nextjs/src/utils/nextImporter.ts

@@ -0,0 +1,3 @@
+import { default as DefaultRouter } from 'next/router';
+
+export const Router = DefaultRouter.default ?? DefaultRouter;

packages/nextjs/test/performance/client.test.ts

@@ -1,6 +1,5 @@
-import { default as Router } from 'next/router';
-
 import { nextRouterInstrumentation } from '../../src/performance/client';
+import { Router } from '../../src/utils/nextImporter';
 
 let readyCalled = false;
 jest.mock('next/router', () => {