QFuture::then(QObject *context, Function &&function) throws "read access violation" when used in chained QFuture

#include <QCoreApplication>
#include <QtConcurrent>

int main(int argc, char* argv[]) 
{
    auto a = QCoreApplication(argc, argv);

    QObject obj(&a);

    QtConcurrent::run(
        [] { qDebug() << "block 0"; }
    ).then(
        [] { qDebug() << "block 1"; }
    ).then(
        &obj, [] { qDebug() << "block 2"; }
    );

    a.exec();
}

block 0
block 1
Exception thrown: read access violation.
**_Mem** was 0xFFFFFFFFFFFFFFFF.