i118671 take emergency exit when local slideshow is disposed from executing macros

slideshow/source/engine/slideshowimpl.cxx

@@ -2051,6 +2051,18 @@ sal_Bool SlideShowImpl::update( double & nNextTimeout )
 
             // process queues
             maEventQueue.process();
+
+            // #118671# the call above may execute a macro bound to an object. In
+            // that case this macro may have destroyed this local sliseshow so that it
+            // is disposed (see bugdoc at task). In that case, detect this and exit
+            // gently from this slideshow. Do not forget to disable the scoped
+            // call to mpPresTimer, this will be deleted if we are disposed.
+            if (isDisposed())
+            {
+                scopeGuard.dismiss();
+                return false;
+            }
+
             maActivitiesQueue.process();
 
             // commit frame to screen