[UEFN CRASH] Cannot modify "external" variables of a subclass accessed via a subtype

Summary

As the title explains, when you try to access a sub-class from a parametric type, the whole UEFN application crashes when you try to compile the Verse code

Please select what you are reporting on:

Unreal Editor for Fortnite

What Type of Bug are you experiencing?

Verse

Steps to Reproduce

  1. Create a class that uses a parametric type of a sub-class that has an external variable:
    widget_manager<public>(W:subtype(widget)) := class:
        Widget<public> : W
        Player<public> : player

        Show<public>() : void =
            if (PlayerUI := GetPlayerUI[Player]):
                PlayerUI.AddWidget(Widget)
  1. Create an instance of the created class:
HudMoney := widget_manager(W_Money):
    Widget := W_Money{}
    Player := Player
  1. Try to change the value of the external variable:
set HudMoney.Widget.MoneyAmount = S2M("Some message...")

Here is what my widget looks like (from Assets.digest.verse):

    W_Money<scoped {/PrivateUsername@fortnite.com/PrivateMap}> := class(widget):
        var MoneyAmount<public>:message = external {}

Expected Result

The verse code should compile without any issues or throw an compiler error

Observed Result

The UEFN app crashes when I click “Build Verse Code” and trying to open the project would instantly crash UEFN because its trying to compile each time you open it

Platform(s)

Windows 11 Pro

FORT-1018063 has been added to our ‘To Do’ list. Someone’s been assigned this task.