According to Osho, waking with a deep fear of death is not a problem but a sign your meditation is deepening. Meditation and death are alike: as awareness grows, the ego dissolves, and that dissolution is first felt as 'I am dying.' Deeper, quieter sleep becomes meditative; on waking, the ego resists and panics. Welcome it; trust your own insight.
Your morning fear means meditation is working—your ego is shrinking, and at first that feels like dying.