swift-existentials.swift

protocol P {
}

struct Q: P {}

struct MyWrapper {
    let key: String
    let value: any P
}

let point: Q? = nil
// 🛑 Value of optional type 'Q?' must be unwrapped to a value of type 'Q'
let wrapper = MyWrapper(key: "point", value: point)

if wrapper.value == nil {
    print("nil value")
} else {
    print("continue…")
}