Yeah, I got it 😊.
Adequate measures have been taken for that. A person needs to write a "Living Will" in advance (when his / her mental state is healthy and without any undue influence) in front of a magistrate to declare his/her intention in advance. A team of medical practitioner (different from the one treating the patient) is required to give declaration that the patient can not be cured of that terminal illness. and some other safety provisions are part of this judgment.