Port away from nested event loops

QGrpcStatus QGrpcCallReply::waitForFinished() const
{
    QEventLoop loop;
    QGrpcStatus status;
    QObject::connect(this, &QGrpcCallReply::errorOccurred, this,
                     [&status, &loop](const QGrpcStatus &error) {
                         status = error;
                         loop.quit();
                     });
    QObject::connect(this, &QGrpcCallReply::finished, &loop, &QEventLoop::quit);    loop.exec();
    return status;
}