/stop in singleplayer brings you in multiplayer menu/crashes the game

When you open a singleplayer and run the /stop command you get an error Message "Connection Lost", "Server closed" with the only option "Back to server list", which brings you to the multiplayer menu, NOT the singleplayer menu.If you play Minecraft in Fullscreen and then do anything outside of Minecraft (pressing the windows key is enough, selecting any other Window works also) while this error message is being displayed your game will crash.