QLoggingCategory::installFilter crashes with the code from documentation

+underlined text+In the documentation example I see the usage of previous filter. I think, it is meant to use in the following way:

oldCategoryFilter = QLoggingCategory::installFilter(myCategoryFilter);

This code leads to crash, as QLoggingCategory::installFilter() call myCategoryFilter() when oldCategoriFilter is not valid yet.
The workaround is to use this code:

oldCategoryFilter = QLoggingCategory::installFilter(Q_NULLPTR);
QLoggingCategory::installFilter(myCategoryFilter);

This is not obvious and looks like a hack, so I think it is either a bug, or should be pointed in documentation.