The most likely cause of death would be a crash landing.
When geese come in for a landing after a long flight they are exhausted and look for lakes or ponds to land on because they can glide in onto the water and come to an easy stop without much effort. For geese to land on solid ground they have to slow their speed significantly and flap a bunch before touching down or they can seriously hurt themselves. One ice geese will tend to ski out the landings a bit because they know the ice is slippery, but they still slow themselves down quite a bit before touching down.
It can be hard for geese sometimes to distinguish between a nice soft liquid lake, and frozen ice depending on the clarity of the ice when it freezes. Geese are not unaccustomed to landing on ice, but when they do they typically slow down more than they would when landing on water and ski out the landing. Tired geese are known to have rough landings every once and a while, even on water, but if they have one flying in on a frozen lake expecting it to be water, and land hard, it can sometimes result in injury, leading to death.
This is the same reason why you'll occasionally find dead geese on football fields that have blue artificial turf. They mistake the turf for a lake and come in for a rough landing.
So the most likely reason your goose is dead could be a crash landing, resulting in an injury that prevented the goose from escaping the freezing cold, which led to the goose's eventual death by exposure and freezing to the ice.