Check for readonly properties

[RV7PR]

In this old issue opis/closure#28 I had a problem with readonly properties so they fixed it with this opis/closure@3.1.5...3.1.6 though this ($property->getDeclaringClass()->isUserDefined()) isn't needed for PHP >= 8.1, you can just skip the readonly properties like #87

[driesvints]

Thanks @RV7PR. @rust17 could this be an alternative implementation?

[rust17]

I believe these are two separate issues.

The $property->getDeclaringClass()->isUserDefined() method solves the Cannot write property problem, whereas $property->isReadOnly() deals with the Cannot modify readonly property issue. As you can see, the opis/closure encounters the Cannot modify readonly property issue during unserialization, similar to what was reported in laravel/framework#51877.

Therefore, I don't think this is an alternative solution.

Additionally, this line of code($property->getDeclaringClass()->isUserDefined()) is already present in laravel/serializable-closure: https://github.com/laravel/serializable-closure/blob/master/src/Serializers/Native.php#L371.

[driesvints]

Thanks @rust17