fix(bidi): guard nullable navigation fields in event handlers

packages/playwright-core/src/server/bidi/bidiPage.ts

@@ -194,14 +194,17 @@ export class BidiPage implements PageDelegate {
 
   private _onNavigationStarted(params: bidi.BrowsingContext.NavigationInfo) {
     const frameId = params.context;
-    this._page.frameManager.frameRequestedNavigation(frameId, params.navigation!);
+    this._page.frameManager.frameRequestedNavigation(frameId, params.navigation || undefined);
   }
 
   private _onNavigationCommitted(params: bidi.BrowsingContext.NavigationInfo) {
     const frameId = params.context;
-    const frame = this._page.frameManager.frame(frameId)!;
+    const frame = this._page.frameManager.frame(frameId);
+    if (!frame)
+      return;
     this._browserContext.doGrantGlobalPermissionsForURL(params.url).catch(error => debugLogger.log('error', error));
-    this._page.frameManager.frameCommittedNewDocumentNavigation(frameId, params.url, frame._name, params.navigation!, /* initial */ false);
+    if (params.navigation)
+      this._page.frameManager.frameCommittedNewDocumentNavigation(frameId, params.url, frame._name, params.navigation, /* initial */ false);
   }
 
   private _onDomContentLoaded(params: bidi.BrowsingContext.NavigationInfo) {

tests/page/page-goto.spec.ts

@@ -254,6 +254,30 @@ it('should navigate to about:blank', async ({ page, server }) => {
   expect(response).toBe(null);
 });
 
+it('should handle navigation with null navigation id in BiDi', async ({ page, server, isBidi }) => {
+  // This test verifies that BiDi navigation events with null navigation are handled gracefully.
+  // In BiDi, navigation can be null for same-document navigations and some edge cases.
+  // Without proper handling, null navigation would be passed to frameManager methods
+  // that expect string or undefined, causing issues.
+  it.skip(!isBidi, 'BiDi-specific test');
+
+  // Test 1: Navigate to about:blank (might have null navigation in some BiDi implementations)
+  await page.goto('about:blank');
+  expect(page.url()).toBe('about:blank');
+
+  // Test 2: Navigate to a real page
+  await page.goto(server.EMPTY_PAGE);
+  expect(page.url()).toBe(server.EMPTY_PAGE);
+
+  // Test 3: Use history.pushState (same-document navigation, navigation is null in BiDi)
+  await page.evaluate(() => history.pushState({}, '', '/pushed'));
+  expect(page.url()).toBe(server.PREFIX + '/pushed');
+
+  // Test 4: Navigate back
+  await page.goBack();
+  expect(page.url()).toBe(server.EMPTY_PAGE);
+});
+
 it('should return response when page changes its URL after load', async ({ page, server }) => {
   const response = await page.goto(server.PREFIX + '/historyapi.html');
   expect(response.status()).toBe(200);