I see the following output by QVariant::setValue() and functions alike:
In this particular case, the assertion is:
ASSERT failure in qRegisterNormalizedMetaType: "qRegisterNormalizedMetaType was called with a not normalized type name, please call qRegisterMetaType instead.", file /home/ag/work/build/qt5_namespaced/qtbase/include/QtCore/../../../../../qt5/qtbase/src/corelib/kernel/qmetatype.h, line 1235
This is due to normalizedTypeName passed to qRegisterNormalizedMetaType() (in QMetaTypeIdQObject<T*, QMetaType::PointerToQObject>::qt_metatype_id()) being unequal to what QMetaObject::normalizedType(normalizedTypeName.constData()).
This happens due to QMetaObject::normalizedType() skipping Qt namespace when it's specified, while normalizedTypeName still uses the Qt namespace.