core: Use Q_ASSERT_X to warn about setting headers after they have been sent
core: Use Q_ASSERT_X to warn about setting headers after they have been sent

cutelyst/cutelyst,cutelyst/cutelyst,buschmann23/cutelyst,simonaw/cutelyst,buschmann23/cutelyst,simonaw/cutelyst,cutelyst/cutelyst,buschmann23/cutelyst