Legal Question in Criminal Law in Texas

You did not give the person the drugs? You did not help the person ingest the drugs? You were sitting or standing there and the person just died? You did not try to help the person by calling police or ambulance?

Off the top of my head I cannot think of any law violated if someone leaves if the person had nothing to do with the situation. (Say went to sleep and when awoke found that friend had OD'd during the night and was dead.) I did research and cannot come up with any obligation.

The only real obligations for the care of another are if you cause the problem, if you are a parent / custodian or in charge of the person, you must seek help. But, your proposal says the person is already dead.

I would just say that if one simply left behind their dead friend then the police would look long and hard at the supposed friend who left.