fix: prevent Basic Functionality modal crash when route params are undefined (#32189)

## **Description**

Turning off Basic Functionality from **Settings → Security & Privacy**
opens `BasicFunctionalityModal` without route params. On confirm,
`closeBottomSheet` read `route.params.caller` and threw when `params`
was `undefined`.

Only the Notifications flow passes a `caller` param; Security Settings
does not. This change uses optional chaining so the
notifications-specific branch runs only when `caller` is present, and
adds a unit test for the undefined-params path.

## **Changelog**

CHANGELOG entry: Fixed a crash when turning off Basic Functionality from
Security & Privacy settings

## **Related issues**

Fixes: crash when disabling Basic Functionality from Security Settings
without modal route params

## **Manual testing steps**

```gherkin
Feature: Basic Functionality modal

  Scenario: user turns off Basic Functionality from Security Settings
    Given the app is unlocked and Basic Functionality is enabled
    When user opens Settings → Security & Privacy → Basic Functionality
    And user confirms they understand and taps Turn off
    Then the modal dismisses without crashing
    And Basic Functionality is disabled

  Scenario: user opens Basic Functionality from Notifications with caller param
    Given the app is unlocked and Basic Functionality is disabled
    When user opens Notifications settings and is prompted to enable Basic Functionality
    And user completes the modal flow
    Then the modal dismisses without crashing
    And the notifications-specific follow-up still runs when applicable
```

## **Screenshots/Recordings**

N/A — crash fix with no visual UI change; verified via unit test and
manual modal dismiss flow.

### **Before**



https://github.com/user-attachments/assets/8e7b171d-2bcb-4bcb-9619-51c36416fb09



### **After**



https://github.com/user-attachments/assets/4518a50f-0c9b-4003-b78a-f17040ece4be



## **Pre-merge author checklist**

- [x] I've followed [MetaMask Contributor
Docs](https://github.com/MetaMask/contributor-docs) and [MetaMask Mobile
Coding
Standards](https://github.com/MetaMask/metamask-mobile/blob/main/.github/guidelines/CODING_GUIDELINES.md).
- [x] I've completed the PR template to the best of my ability
- [x] I've included tests if applicable
- [x] I've documented my code using [JSDoc](https://jsdoc.app/) format
if applicable
- [x] I've applied the right labels on the PR (see [labeling
guidelines](https://github.com/MetaMask/metamask-mobile/blob/main/.github/guidelines/LABELING_GUIDELINES.md)).
Not required for external contributors.

#### Performance checks (if applicable)

- [x] I've tested on Android
  - Ideally on a mid-range device; emulator is acceptable
- [x] I've tested with a power user scenario
- Use these [power-user
SRPs](https://consensyssoftware.atlassian.net/wiki/spaces/TL1/pages/edit-v2/401401446401?draftShareId=9d77e1e1-4bdc-4be1-9ebb-ccd916988d93)
to import wallets with many accounts and tokens
- [x] I've instrumented key operations with Sentry traces for production
performance metrics
- See [`trace()`](/app/util/trace.ts) for usage and
[`addToken`](/app/components/Views/AddAsset/components/AddCustomToken/AddCustomToken.tsx#L274)
for an example

For performance guidelines and tooling, see the [Performance
Guide](https://consensyssoftware.atlassian.net/wiki/spaces/TL1/pages/400085549067/Performance+Guide+for+Engineers).

## **Pre-merge reviewer checklist**

- [ ] I've manually tested the PR (e.g. pull and build branch, run the
app, test code being changed).
- [ ] I confirm that this PR addresses all acceptance criteria described
in the ticket it closes and includes the necessary testing evidence such
as recordings and or screenshots.

<!-- CURSOR_SUMMARY -->
---

> [!NOTE]
> **Low Risk**
> Single optional-chaining guard and a focused unit test; no auth, data,
or broader navigation behavior changes beyond avoiding the crash.
> 
> **Overview**
> Fixes a crash when users turn off Basic Functionality from **Settings
→ Security & Privacy**, where the modal opens **without** navigation
route params.
> 
> `closeBottomSheet` now uses optional chaining on
`route.params?.caller` so the notifications-only follow-up
(`enableNotificationsFromModal`) runs only when a `caller` is present,
instead of throwing on `undefined.params`.
> 
> Adds a unit test that mocks `useRoute` with `params: undefined` and
asserts **Turn off** still dispatches `toggleBasicFunctionality(false)`.
> 
> <sup>Reviewed by [Cursor Bugbot](https://cursor.com/bugbot) for commit
54f2b84. Bugbot is set up for automated
code reviews on this repo. Configure
[here](https://www.cursor.com/dashboard/bugbot).</sup>
<!-- /CURSOR_SUMMARY -->

Author: asalsys

app/components/UI/BasicFunctionality/BasicFunctionalityModal/BasicFunctionalityModal.test.js

@@ -86,4 +86,17 @@ describe('BasicFunctionalityModal', () => {
 
     expect(toggleBasicFunctionality).toHaveBeenCalledWith(false);
   });
+
+  it('turns off basic functionality when route params are undefined', () => {
+    mockRouteParams = undefined;
+
+    const { getByText } = renderWithProvider(<BasicFunctionalityModal />, {
+      state: mockInitialState,
+    });
+
+    fireEvent.press(getByText('I understand and want to continue'));
+    fireEvent.press(getByText('Turn off'));
+
+    expect(toggleBasicFunctionality).toHaveBeenCalledWith(false);
+  });
 });

app/components/UI/BasicFunctionality/BasicFunctionalityModal/BasicFunctionalityModal.tsx

@@ -95,7 +95,7 @@ const BasicFunctionalityModal = () => {
           .build(),
       );
     });
-    if (route.params.caller === Routes.SETTINGS.NOTIFICATIONS) {
+    if (route.params?.caller === Routes.SETTINGS.NOTIFICATIONS) {
       await enableNotificationsFromModal();
     }
   };