AccessorDescriptor properties may have their get & set properties defined to reference a function (Callable object) or, or be set to undefined. Valid PropertyDescriptors created by toPropertyDescriptor (defined from JS code via Object.defineProperty, etc) have get and set properties that are in one of three states (1) nonexistent (c++ null JSValue), (2) JS undefined, or (3) a function (or any Callable).
Created attachment 122178 [details] Fix
Fixed in r104836