How can I die upon accessing a non-existing key in a deep Hoh as Moose attribute?

Generally I'd say, if you have a complex data structure that you want to handle in an object oriented manner, you should turn the data structure into a tree of objects. With Moose coercions this can be modeled rather transparently as well.

You could look at turning off autovivification through autovivification.

I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.