Don't try to create tab if windowId is falsey
Don't try to create tab if windowId is falsey

Fixes https://github.com/brave/browser-laptop/issues/8545

Auditors: @mrose17

Test plan:
1. Ensure Payments are enabled and Open `about:blank`
2. From the `Shields` menu, pick `Site Shield Settings...`
3. Verify nothing happens and that the app doesn't crash

luixxiul/browser-laptop,diasdavid/browser-laptop,luixxiul/browser-laptop,timborden/browser-laptop,diasdavid/browser-laptop,luixxiul/browser-laptop,diasdavid/browser-laptop,timborden/browser-laptop,timborden/browser-laptop,luixxiul/browser-laptop,timborden/browser-laptop,diasdavid/browser-laptop