C#: CSharpScript.CanInstantiate() returns true for abstract classes but .New() throws at runtime

[juse4pro]

Godot version

v4.1.beta1.mono.official [828ec2c]

System information

Windows 11

Issue description

When I call .CanInstantiate() on a CSharpScript object it returns true even though it can't be instantiated via .New() when the class is abstract. I get a runtime exception: MemberAccessViolation: Cannot create an abstract class. (see attachment)

I would expect that .CanInstantiate() only returns true when I actually can instantiate it.

Steps to reproduce

• Get some kind of CSharpScript (e.g. via ResourceLoader)
• Call .CanInstantiate() on it / print it
• Call .New() on it
• Get exception

Minimal reproduction project

CanInstantiateBug.zip

[AThousandShips]

The script system doesn't seem to have any concept of abstractness, and the function doesn't test anything like that in CSharpScript, so seems like a missing functionality, would be supported if abstract classes were added to GDScript probably:

• Add support for abstract classes in GDScript godot-proposals#5641

[RedworkDE]

Also IIRC there was an issue for pretty much the same thing with gdscript where for core types can_instantiate returns true, but it is not actually possible to do so, can't find it rm tho,

[AThousandShips]

Was it:

• ClassDB.can_instantiate should report false on these classes. #77402

[juse4pro]

I can understand that GDScript does not support the concept of abstraction yet. But to be honest when a method says Returns true if the script can be instantiated. but I can't instaniate it I would expect that the CSharpScript implementation overrides it in a way that the abstract marking is checked. Because this way the API just delivers a wrong information.

So I think it more a bug seen from this perspective.