bug: IonTabs throws when a Fragment contains one IonRouterOutlet

### Prerequisites

- [x] I have read the contributing guidelines.
- [x] I agree to follow the Code of Conduct.
- [x] I searched existing issues without finding this problem.

### Ionic Framework Version

v8.x, v9.x, Nightly

### Current Behavior

When `IonRouterOutlet` is the only child of a React Fragment passed to `IonTabs`, rendering throws:

```text
TypeError: Cannot read properties of undefined (reading 'type')
```

`IonTabs` treats the Fragment's children as an array, but React stores a single child as an element.

### Expected Behavior

`IonTabs` should render when `IonRouterOutlet` is wrapped in a single-child Fragment.

### Steps to Reproduce

1. Clone the reproduction.
2. Run `npm install` and `npm run dev`.
3. Open the app.

### Code Reproduction URL

https://github.com/Benziza/ion-tabs-fragment-repro

### Ionic Info

```text
Ionic CLI : 7.2.1
Ionic Framework : @ionic/react 9.0.1
NodeJS : v25.6.0
npm : 11.12.1
OS : Windows 10
```

### Additional Information

Removing the Fragment allows the same app to render.

Start with the IonTabs implementation and reproduce the failure using the linked app with npm install and npm run dev. Confirm the fix by rendering an IonRouterOutlet as the only child in a React Fragment passed to IonTabs without the TypeError.

索引モデルが issue の本文から書いたものです。