Failable Codable initialiser for RawRepresentable types

RawRepresentable.swift

extension RawRepresentable where RawValue: Decodable {
    init?(from decoder: Decoder) throws {
        self.init(rawValue: try decoder.singleValueContainer().decode(RawValue.self))
    }
}

enum Enum: String, Codable {
    case aValidCase, anotherValidCase, unknown

    init(from decoder: Decoder) throws {
        self = try Enum(from: decoder) ?? .unknown
    }
}

struct Struct: Codable {
    let property: Enum
}

let json = """
{
    "property": "anInvalidCase"
}
"""

do {
    let s = try JSONDecoder().decode(Struct.self, from: Data(json.utf8))
    print(String(describing: s.property.rawValue))
} catch {
    print(error)
}