This is a follow up to
OAK-3349: in tail compaction the FileStore.GarbageCollector.getBase() might fail to determine the base state to rebase onto. In this case we should fall back to full compaction and report (log, JMX) the problem and its exact cause.
Failing to determine the base state might be caused by a missing or invalid gc.log file or a invalid or missing record id for the base state being recorded in gc.log. None of these cases should impact system stability.