The Q*Application instance should be destroyed before main() returns
This came up discussing an issue that came up using mscore with a 3rd party Qt plugin not directly related to mscore itself on the Qt interest ML.
Qt assumes that the QCoreApplication instance is destroyed before main() returns; doing this resets qApp to nullptr. Any plugin accessing the instance via qApp during global destruction as part of its cleanup work is likely to access memory that has become invalid and provoke a crash.
While my exact way of triggering this isn't likely to be encountered by many other users it's still a dormant bug that should be addressed.