About the issue where your game is showing as having deleted DLC's or lost game totally. Go to your Steam app. Go to Steam < Settings < Downloads < Clear Download Cache. This should restart Steam and you should have access to your game & DLCs.
In no way should the trapper be allowed to put traps here, you can't undo the trap and he can still hit you from there. It is more than just unfair for survivors but an issue when this was a spot survivors got banned for in the past.