UnsafeContinuation<T>にして
func withUnsafeContinuation<T>( operation: (UnsafeContinuation<T, Never>) -> () ) async -> T func withUnsafeThrowingContinuation<T, E: Error>( operation: (UnsafeContinuation<Result<T, E>>) throws -> () ) async throws -> T にすれば、throwsで受けることもResultで受けることもできそうだ