Assert the request have a valid normalized rect

core/document.cpp

@@ -1101,6 +1101,7 @@ void DocumentPrivate::sendGeneratorPixmapRequest()
 
             // Change normalizedRect to the smallest rect that contains all
             // visible tiles.
+            Q_ASSERT( !r->normalizedRect().isNull() )
             if ( !r->normalizedRect().isNull() )
             {
                 NormalizedRect tilesRect;