bug: vue swipe cancellation throws when the previous page is missing #31514

Prerequisites

• I have read the contributing guidelines and code of conduct.
• I have searched existing issues for this problem.

Ionic Framework Version

v9.x

Current Behavior

Ionic Vue's IonRouterOutlet cancellation branch (swipeHandler.onEnd(false)) unconditionally dereferences the view returned by findViewItemByRouteInfo and its ionPageElement.

If the callback runs after navigation has returned to a root route, there may be no previous view in that outlet. The callback throws:

TypeError: Cannot read properties of undefined (reading 'ionPageElement')

The same branch also throws if a view record exists but its page has been unmounted. This was observed in an iOS app using 9.0.3, with the stack pointing to the cancelled-animation callback in the core router outlet. The unguarded code is still present on main at 643584b3ac2ba1ca263cbf53960ccde3be2a96fc (9.0.6).

Expected Behavior

Cancellation should safely do nothing if there is no previous mounted page to hide. When the page exists, cancellation should continue setting aria-hidden="true" and ion-page-hidden. Completed swipes should continue navigating back.

Steps to Reproduce

1. Download the four files in the reproduction gist into one directory.
2. Run npm install and npm run dev with a supported Node version.
3. Open the displayed local URL and click Reproduce.
4. Observe the TypeError in the page and console.

The reproduction uses the real Ionic Vue router and outlet. It pushes a second page, checks canStart(), returns to the first page, then explicitly delivers onEnd(false) to model a late cancellation callback. This is a deterministic callback-level reproduction, not a claim to reproduce the physical touch/animation race. There are no mocked view stacks or routers.

Code Reproduction URL

https://gist.github.com/dandoingdev/d7a6e044bf006bdb633aa32aaeffd410

Environment

Standalone reproduction: @ionic/vue 9.0.6, @ionic/vue-router 9.0.6, Vue 3.5.42, Vue Router 5.3.1, Vite 8.3.0. Confirmed in headless Chrome on macOS. No Ionic CLI or Capacitor is needed for the deterministic reproduction.

Additional Information

I have prepared a small guard for the missing view/page and regression tests, and will link the PR here. Tests cover missing views, unmounted pages, normal cancellation cleanup, completed swipes, and late cancellation after returning to the root using the real router.