Inconsistent handling of property initialisation vs binding

There are several cases in which an initialisation together with property declaration is not allowed, but a subsequent binding is ok.

I fear this is due to inconsistencies arising in the grammar, but currently

type with <> -> initialisation is expected to be an object list

type without <> -> initialisation can be object or sort expression.

default and required and readonly limit this further.

If no inconsistency arises then I feel that we should (from the grammar point of view) always allow all kind of initialisations, and warn later about them.

The current state requires strange checks (see https://codereview.qt-project.org/c/qt/qtdeclarative/+/373578 ) Some of the non allowed things in the initialisation are (but allowed when split) are:

property list<Item> myList: Item{}
property var arrayNoMerge: [Item {}, Item\{ nr: 2 }]
default property list<Item> nonMergeable: [Item {}, Item\{ nr: "II" }]