Add GameConfig validation

mavenmcserver/src/main/java/mavenmcserver/command/CommandTicTacToe.java

@@ -53,6 +53,7 @@ public boolean onCommand(CommandSender sender, Command command, String label, St
 				if(args[0].equals(noAvailablePlayersPlaceholder[0]) && args[1].equals(noAvailablePlayersPlaceholder[1]) && args[2].equals(noAvailablePlayersPlaceholder[2])) return true;
 			}
 
+			// Create the game's config from the command's args
 			GameConfig config;
 
 			try {
@@ -66,6 +67,18 @@ public boolean onCommand(CommandSender sender, Command command, String label, St
 				return true;
 			}
 
+			// Check for errors in the game's config
+			List<String> configErrors = config.validate();
+			if(!configErrors.isEmpty()) {
+				for(String error: configErrors) {
+					sender.sendMessage(ChatColor.RED + error + ChatColor.RESET);
+				}
+
+				// Don't continue on error
+				return true;
+			}
+
+			// Show the config to the player
 			sender.sendMessage("You just executed /tictactoe correctly");
 			sender.sendMessage("Opponent player name: '" + config.opponentPlayer.getName() + "'");
 			sender.sendMessage("Game size: " + config.size);

mavenmcserver/src/main/java/mavenmcserver/game/GameConfig.java

@@ -1,5 +1,8 @@
 package mavenmcserver.game;
 
+import java.util.ArrayList;
+import java.util.List;
+
 import org.bukkit.entity.Player;
 import org.joml.Vector3i;
 
@@ -15,4 +18,15 @@ public GameConfig(Player mainPlayer, Player opponentPlayer, Vector3i size, int w
 		this.size = size;
 		this.winRequiredAmount = winRequiredAmount;
 	}
+
+	/// Returns an empty list if everything is OK.
+	public List<String> validate() {
+		ArrayList<String> errors = new ArrayList<String>();
+
+		if(this.winRequiredAmount < this.size.maxComponent()) {
+			errors.add("The required win amount must not be larger than the size's largest dimension");
+		}
+
+		return errors;
+	}
 }