This is such a cool concept and aasm has so many stars on github, but I can't really imagine how this can be used a practical Rails setting. It feels like something the ActiveRecord callbacks or validations can achieve. Ultimately it seems to be providing some form of lifecycle hook?

One thought, let's say you have a very complicated application (think ERP) and you have an onboarding wizard. This can take some companies a long time to complete and things need to happen in a certain order. As some stages are completed, a lot of background API calls are made and data is synchronized. Using State Machines may be a viable solution in these kinds of scenarios.

Any Idea how to catch this error on controller and send specific message?