macOS: Crash in QVariant::fromValue when called in a plugin with an object defined in a shared library

I have the following use case (source code attached):

A Qt plugin that uses a shared library (named sdk) and the plugin provides some functionality for the main app that loads it. If the plugin calls `QVariant::fromValue` and sends as parameter an object which is defined in the shared library, the application crashes when loading the plugin the second time (Load -> Unload -> Load => crash).

I have noticed that if the the library linked from the plugin is compiled statically the application does not crash. Also, if the object passed as parameter to `QVariant::fromValue` does not have the default constructor, the copy constructor and the destructor defined the crash does not appear.

I wasn't able to figure out the cause of the problem in my app, I suppose there's something wrong in `QVariant`.