Sorry for your loss OP, whatever the circumstances it's never easy.
I'd always hope such a question is coming from a place of kindness, or at worst neutrality. When we say someone died "unexpectedly", I think that's the crux - it wasn't expected, so in the most basic of terms there probably wasn't an obvious illness / health concern that we all knew of, or of an age where it would be realistic. I think its human nature to then try to figure something out, piece together the unknown.
Of course, that doesn't take away your right as the bereaved to choose not to share detail, either because you don't want to for whatever reasons or as another poster suggested with her friend, that your person wouldn't want their private / health information shared.
For what it's worth, I was the visitor once to someone who was bereaved, not quite in a professional capacity but similar. I knew they'd had a "sudden & tragic bereavement" but nothing else, not even whether anyone living with who i was visiting was similarly bereaved. I expressed genuine condolences, and she asked me if I knew what had happened, I said "no, wasn't my place to ask detail before - but happy to listen if you want to talk". She did - and told me of her child, their life, troubles etc. She didn't say an explicit cause of death - I could probably have guessed - but that doesn't change her grief or the situation she's now in.
So, I suppose that's to say, hopefully no-one is meaning to be genuinely intrusive with the question - and that you can have conversations where you can talk of your loved one in a way that's helpful to you. But also that you'll undoubtedly feel rage or anger - even in situations others say is OK, and its OK you feel angry.