[Bug]: Install - `TypeError: Cannot read properties of undefined (reading 'getSelf')`

### Describe the bug

Whenever I import the Extension for the first time, if I open the offscreen.html I get the following error `TypeError: Cannot read properties of undefined (reading 'getSelf')`

### Expected behavior

No error

### Screenshots/Recordings

https://github.com/user-attachments/assets/ca4f361f-ceda-49d0-b455-8f49d1084903

### Steps to reproduce

1. Import a MM build
2. Open the offscreen.html
3. See error

### Error messages or log output

```shell
TypeError: Cannot read properties of undefined (reading 'getSelf')
```

### Where was this bug found?

Internal release testing

### Version

found in 13.28.0 but might be already in prod, but I haven't seen any Sentry entries

### Build type

None

### Browser

Chrome

### Operating system

MacOS

### Hardware wallet

_No response_

### Additional context

_No response_

### Severity

_No response_

[Jira issue](https://consensyssoftware.atlassian.net/browse/MCTP-270)

### Expected behavior

No response

### Screenshots/Recordings

No response

### Steps to reproduce

1. Import a MM build
2. Open the offscreen.html
3. See error

### Error messages or log output

```shell
TypeError: Cannot read properties of undefined (reading 'getSelf')
```

### Where was this bug found?

No response

### Version

found in 13.28.0 but might be already in prod, but I haven't seen any Sentry entries

### Build number

No response

### Build type

None

### Browser

Chrome

### Operating system

MacOS

### Hardware wallet

No response

### Additional context

No response

### Severity

Sev2

Reproduce the issue in Chrome by importing a MetaMask build and opening offscreen.html, then locate the code path that reads getSelf. Confirm the fix by opening offscreen.html again and verifying that the TypeError no longer appears.

Written by the indexing model from the issue text.