when Prism procs a damage effect, one of the types of "damage" it can pick is Repair, which can heal any enemy type. when it goes off you see a green number on the target with the wrench icon.
so aside from the fact that repair energy is not a damage type, so shouldn't be one of the damage types that can happen just like positive isn't one of the types that procs, non constructs really shouldn't be healed from repair.
I have had multiple lives using Prism through epics and see this go off regularly