Fix player count not updating on player logout

The player is still on the player list when the logged out event fires,
so an offset needs to be applied.

src/main/java/dev/sciwhiz12/concord/ChatBot.java

@@ -93,7 +93,7 @@ public MinecraftServer getServer() {
 
     @Override
     public void onReady(ReadyEvent event) {
-        this.updateActivity();
+        this.updateActivity(0);
 
         Concord.LOGGER.debug(BOT, "Checking guild and channel existence, and satisfaction of required permissions...");
         // Required permissions are there. All checks satisfied.
@@ -194,8 +194,8 @@ boolean checkSatisfaction() {
     }
 
     @ApiStatus.Internal
-    public void updateActivity() {
-        final int playerCount = server.getPlayerList().getPlayers().size();
+    public void updateActivity(int offset) {
+        final int playerCount = server.getPlayerList().getPlayers().size() + offset;
         final Component message = Messages.BOT_STATUS_ONLINE.eagerComponent(playerCount);
         // TODO: make the activity type adjustable
         discord.getPresence().setPresence(OnlineStatus.ONLINE, Activity.playing(message.getString()));

src/main/java/dev/sciwhiz12/concord/msg/PlayerListener.java

@@ -49,7 +49,7 @@ public PlayerListener(ChatBot bot) {
     @SubscribeEvent(priority = EventPriority.LOWEST)
     void onPlayerLogin(PlayerEvent.PlayerLoggedInEvent event) {
         if (event.getEntity().getCommandSenderWorld().isClientSide()) return;
-        bot.updateActivity();
+        bot.updateActivity(0);
         if (!ConcordConfig.PLAYER_JOIN.get()) return;
 
         Component text = Messages.PLAYER_JOIN.component(event.getEntity().getDisplayName());
@@ -60,7 +60,8 @@ void onPlayerLogin(PlayerEvent.PlayerLoggedInEvent event) {
     @SubscribeEvent(priority = EventPriority.LOWEST)
     void onPlayerLogout(PlayerEvent.PlayerLoggedOutEvent event) {
         if (event.getEntity().getCommandSenderWorld().isClientSide()) return;
-        bot.updateActivity();
+        // The player is still on the player list during this event, so offset to account for it
+        bot.updateActivity(-1);
         if (!ConcordConfig.PLAYER_LEAVE.get()) return;
 
         Component text = Messages.PLAYER_LEAVE.component(event.getEntity().getDisplayName());