Adds ability to decode array allowing invalid elements

DecodeArrayAllowingInvalidElements.swift

extension KeyedDecodingContainer {

    struct Safe<Base: Decodable>: Decodable {
        public let value: Base?

        public init(from decoder: Decoder) throws {
            do {
                let container = try decoder.singleValueContainer()
                self.value = try container.decode(Base.self)
            } catch {
                self.value = nil
            }
        }
    }

    func decode<T: Decodable>(_ type: [T].Type, forKey key: KeyedDecodingContainer.Key, allowInvalidElements: Bool) throws -> [T] {
        guard allowInvalidElements else {
            return try decode(type.self, forKey: key)
        }

        let decoded = try decode([Safe<T>].self, forKey: key).compactMap { $0.value }
        return decoded
    }

    func decodeIfPresent<T: Decodable>(_ type: [T].Type,
                                       forKey key: KeyedDecodingContainer.Key,
                                       allowInvalidElements: Bool) throws -> [T]? {
        guard allowInvalidElements else {
            return try decodeIfPresent(type.self, forKey: key)
        }

        let decoded = try decodeIfPresent([Safe<T>].self, forKey: key)?.compactMap { $0.value }
        return decoded
    }
}