Addresses wrong results issue described in #48

[alex-kulakov]

Resolves #48

Basically it adds checks for Entity/Structure constants where it should be checked and this prevents wrong results

[AlexUstinov]

Does it make sense to test more complex cases like

.Select( a => a.Author ?? a.NoAuthor ?? nullAuthor)
// -or-
.Select( a => a.Author ?? nullAuthor ?? a.NoAuthor)

And the same for the ternary operator. And the ternary operator can have some other condition rather than null comparison. At least it would help to avoid IDE warnings.

[alex-kulakov]

Does it make sense to test more complex cases like

.Select( a => a.Author ?? a.NoAuthor ?? nullAuthor)
// -or-
.Select( a => a.Author ?? nullAuthor ?? a.NoAuthor)

And the same for the ternary operator. And the ternary operator can have some other condition rather than null comparison. At least it would help to avoid IDE warnings.

Such complex test cases do make sense, I'll add it. Speaking of null comparison I just used most common one, it does not matter since root of the issue is a local entity/structure.