requestBorrowConfirmation returned `true` (approve the borrow) when
`chrome.tabs.get(tabId)` threw. That fail-open was not one of the
documented fail-open cases in the function's own doc comment (no
candidate window; abort signal; timeout), and the tab was already
fetched successfully moments earlier by the borrow pipeline
(validateBorrowTarget), so a failure here is a transient SW/page hiccup
— not a missing tab. Silently approving a borrow with no confirmation
UI shown defeats the entire human-in-the-loop gate for seizing a user's
logged-in tab.
On a tabs.get failure, fall back to a generic title (the numeric tab id)
and still run the overlay + OS-notification confirmation flow so the
user gets a real chance to approve or deny.
Adds two regression tests (both fail on the unpatched code). Full
extension suite green (361 tests).
Co-Authored-By: Claude <noreply@anthropic.com>
