Resolves: tdf#93474 crash on importing a macro library

its a SfxLibrary which is not a XLibraryContainer

(a SfxLibraryContainer is however)

I think the issue is simply an empty name making code go down the container
rather than library route.

Change-Id: Ib0245d402fe375ac26ab9f2b14fe708b2a34a7a7

basic/source/basmgr/basmgr.cxx

@@ -255,6 +255,7 @@ void SAL_CALL BasMgrContainerListenerImpl::elementInserted( const container::Con
     if( bLibContainer )
     {
         uno::Reference< script::XLibraryContainer > xScriptCont( Event.Source, uno::UNO_QUERY );
+        if (xScriptCont.is())
             insertLibraryImpl(xScriptCont, mpMgr, Event.Element, aName);
         StarBASIC* pLib = mpMgr->GetLib( aName );
         if ( pLib )