Error in RefreshPolicy can lead to IndexNode lock leak

IndexNode uses a ReadWriteLock which is "acquired" and "released".

 boolean acquire() {
        lock.readLock().lock();
        if (closed) {
            lock.readLock().unlock();
            return false;
        } else {
            refreshPolicy.refreshOnReadIfRequired(refreshCallback);
            return true;
        }
    }

Its possible that any exception thrown in RefreshPolicy#refreshOnReadIfRequired can lead to lock being acquired but not released causing the lock to be lost and any further attempt to close such IndexNode instance would block indefinitely.

As a fix the acquire call should account for any potential exception thrown in any call made from within that method call