QAbstractItemView::setModel() has 2 asserts in lines 699 and 703, which do sanity checks on given model. Unfortunately, these asserts do not take dynamic models into account, which require a call to canFetchMore()/fetchMore() to populate their data and assume such call will be made before a call to index(). This situation leads perfectly fine models to crash, when Q_ASSERT_X is enabled and work as intended when disabled.