It would be very unlikely for a person to die in their sleep from asthma.
When you're having asthma attacks the asthma attack would wake the person up so you would be awake when having the asthma attack and hopefully be able to get treatment for it.
The only way you would really be able to die in your sleep due to an asthma attack are if you're heavily sedated for some reason.
That would be the only way to die from an asthma attack during your sleep because if you're not sedated the asthma attack would wake you up.
So yes it's possible to die in your sleep from asthma but it's very rare that someone does die in their sleep from asthma.