So if a friend or someone dear to you is really sick and suffering from some incurable illness (

That's a tough one, because I would want to do a mental assessment first, since many in that situation would not be in the right place mentally to make such a decision... but of course many would argue how do you not expect somebody like that to not be depressed as well or suffer from some other mental illness?
On one hand it's good to think that when you can have nothing else in life, you can at least be given the right to choose your own death, when, where, how, whom you want around. It's an honourable and dignified thing.
On the other hand we could say that there is nothing worse than death and it can never be a "good death" (=euthanasia) under any circumstances.
I've learned palliative care, so I think I would go with that, just doing anything I could so that there would be no pain. I'd ask the person how do they want to be when the time comes before their death. Most likely they'd rather be at home with their loved ones. I'd try to help them achieve that. Chances also are that if somebody comes to that, there is not too much time left for them anyway. So I'd take up all the measures needed, sometimes that means that the person is prescribed many medications for the pain and this causes them to sleep a lot while it can also lead up to apnea. But this is in no way considered assisted suicide or even active euthanasia. It's a natural death.
Some years ago, I'd answer the same thing as you, and maybe my opinion will change over the years again, but for now I'd go with other options like I described.