There was laughter, and smiles, and the kind of small competitions that are less for practical purposes as for mental relief. In all of yesterday afternoon’s fun and games, there was no way to know that just 15 hours prior, on the same ice at the CONSOL Energy Center, the same group of Islanders were finishing up an ugly and thorough beating at the hands of the Penguins. The Isles lost, 5-0, and went down in their first-round, best-of-seven series 1-0. “No sense in dwelling on it,” defenseman Travis Hamonic told The Post after the short practice. “If you lose a game 1-0 in six overtimes or if you lose 10-0, it amounts to the same thing at this point. I think we’re a team that plays a lot better when we’re loose and having fun and just kind of playing. I think we can get back to that.” For all of the Islanders’ youth and inexperience, they know what they have been through this season and what it’s going to take to keep it going, starting tonight in Game 2. “Let’s be honest, this year really hasn’t been roses for us,” Hamonic said. “We had a good stretch there for three weeks, a month. Besides that, it’s been all up and down and we’ve had to face some issues as a group.”