kennethk I suspect my problem is exacerbated by my using Moose for my object type. My case would be best represented by two more layers deep from the class 'Phases' where '$my', '$closure', and '$our' were built from other classes and within each of those class instances they had stored instances of each other in variables. Based on a troubleshooting suggestion provided by fishmonger I think I have traced the failing portion to the equivalent phase in your example at

I now believe the root cause to be the several interlinked attributes i just outlined that are trying to unwind themselves as part of the master class unwind after they have already been cleaned up when they went out of scope before. (At the equivalent 'Phases DESTROY my' and 'Phases DESTROY closure' point in the example.) Unfortunately, an attempt to write a simple case demonstrating my suspicions did not fail. My next steps are to clean up some of the not so pretty architectural decisions I made in an effort to arrive at a lower level of complexity which I hope will either quit failing or yield a cleaner understanding of the problem. Worst case I should be able to submit a simpler question next time.