object is invalid error when new_object argument .parent is assigned S7_object instead of S7_object()

[tschwarzl]

I would like to report a user error which leads to creation of seemingly valid S7 object, however, throws an error later.

When within the S7 constructor the function new_object is called and .parent is assigned S7_object instead of S7_object() a class is created without error.
However, when assigning a property to an object of said class it can lead to object is invalid: - Underlying data is corrupt error.

Unfortunately, (and to my surprise) I was not able to create a minimal example reproducing the error so far.

To prevent other users running into this rather hard to debug problem, I would like to discuss a type check for .parent

> class(S7_object)
[1] "S7_class"  "S7_object"
> class(S7_object())
[1] "S7_object"