Gun.io Software Developer interview questions

Met and had a great conversation with an engineer with ample time to discuss our engineering practices and surface level details on my past projects. Followed by a sadistic Codility test that appeared easier than it is. I completed it relatively quickly and passed the provided unit tests. However it failed when I submitted and I was fobbed off with an email. As a former technical co-founder I've realized these puzzle tests are extremely poor indicators for talent and I feel sad for the engineer who wasted an hour of his time to chat with me beforehand.