Add default reply in commands

src/main/java/com/github/jie65535/openchat/commands/ChatPlayerCommands.java

@@ -43,6 +43,8 @@ public class ChatPlayerCommands implements CommandHandler {
             set.add(targetPlayer.getUid());
             OpenChatPlugin.getInstance().saveData();
             CommandHandler.sendMessage(sender, "OK");
+        } else {
+            sendUsageMessage(sender);
         }
     }
 }

src/main/java/com/github/jie65535/openchat/commands/ChatServerCommands.java

@@ -98,6 +98,7 @@ public class ChatServerCommands implements CommandHandler {
                 plugin.loadConfig();
                 CommandHandler.sendMessage(sender, "OK");
             }
+            default -> sendUsageMessage(sender);
         }
     }
 }