Fix LLThreadSafeQueueInterrupt in WorkQueueBase::postTo during shutdown by...

Fix LLThreadSafeQueueInterrupt in WorkQueueBase::postTo during shutdown by catching and returning false

indra/llcommon/workqueue.h

@@ -516,6 +516,8 @@ namespace LL
         // Here we believe target WorkQueue still exists. Post to it a
         // lambda that packages our callable, our callback and a weak_ptr
         // to this originating WorkQueue.
+        try
+        {
             tptr->post(
                 [reply = super::getWeak(),
                  callable = std::move(callable),
@@ -547,6 +549,12 @@ namespace LL
                 },
                 // if caller passed a TimePoint, pass it along to post()
                 std::forward<ARGS>(args)...);
+        }
+        catch (const Closed&)
+        {
+            // target WorkQueue still exists, but is Closed
+            return false;
+        }
 
         // looks like we were able to post()
         return true;