Accessing destroyed value in a method connected to a Signal results in a crash.

While attempting to reproduce QTBUG-29676 I ran into the issue. Scenario is quite similar to what's being described in the aforementioned bug. Roughly:

1. An Object A has a field F and a method M accessing that field F
2. M is being connected to the signal S
3. A is being destroyed
4. Signal S is being emitted -> M is being called trying to access F (which is null)

Here I am attaching a reproducible crash setup. (After clicking on "Say hello" the app crashes)

There is no crash when Cachegen is disabled though.