Make it possible to switch deinit warning message off by default

[ghost]

This message: PromiseSource.deinit: WARNING: Unresolved PromiseSource deallocated, maybe retain this object? appears in our test suite log often, which makes the test results difficult to read. The warning is useful in a production context, but not while testing. It would be nice to be able to disable the warning globally. Although we could disable the warning on an instance-by-instance basis, we would prefer to not need to change the construction of promises throughout the codebase.

[tomlokhorst]

Hmm... interesting, I've asked around a bit, but none of my colleagues at Q42 have run in to this exact issue.
In test environments we already have a bunch of switches to change things from production. So perhaps that's why this never came up.

Thinking about this, I can't think of a way of changing the default warning, without introducing global mutable state, which in my opinion is a bad idea. Do you have a proposed solution?

I'm working on improving the deinit warnings. Where next to the print, you can also set it to either a fatalError, or add a callback. Perhaps that's also of use to you?

Thanks for using Promissum and taking the time to create this issue!