Changed error message.

app/semipublic/game.html

@@ -47,7 +47,7 @@
         document.querySelector("#join-game").onclick = () => {
             socket.emit("join game", null, (duplicate) => {
                 if (duplicate) {
-                    document.querySelector("#error-container").textContent = "Sorry, but you logged in as a duplicate user.";
+                    document.querySelector("#error-container").textContent = "Already joined game.";
                     document.querySelector("#player-info-container").style.display = "none";
                     document.querySelector("#board-container").style.display = "none";
                 }