Program crash: GC destroys an object unexpectedly

[eugene]

On Tuesday, 14 September 2021 at 12:09:03 UTC, Steven 
Schveighoffer wrote:
> This project is too big and complex for me to diagnose by just 
> reading, it would take some effort

take a look at

https://www.routledge.com/Modeling-Software-with-Finite-State-Machines-A-Practical-Approach/Wagner-Schmuki-Wagner-Wolstenholme/p/book/9780367390860#

'Event/Message Driven State Machines'
(http://zed.karelia.ru/mmedia/bin/edsm-g2-rev-h.tar.gz)
was inspired by this nice book.