Decided to store the Player UUID instead of the Player Object

Since it's more reasonable and better to work with when handling data.
Also, the command can only be used one time per death.

pom.xml

@@ -6,7 +6,7 @@
 
     <groupId>club.frozed.lunarapi</groupId>
     <artifactId>LunarClientUtils</artifactId>
-    <version>1.1-SNAPSHOT</version>
+    <version>1.2-SNAPSHOT</version>
     <packaging>jar</packaging>
 
     <name>LunarClientUtils</name>

src/main/java/club/frozed/lunarutils/commands/BackCommand.java

@@ -8,6 +8,7 @@
 import org.bukkit.entity.Player;
 
 import java.util.HashMap;
+import java.util.UUID;
 
 /**
  * Created by Elb1to
@@ -16,15 +17,21 @@
  */
 public class BackCommand extends BaseCommand {
 
-    public static HashMap<Player, Location> playerLocation = new HashMap<>();
+    public static HashMap<UUID, Location> playerLocation = new HashMap<>();
 
     @Command(name = "back", aliases = {"backpos", "goback"})
 
     @Override
     public void onCommand(CommandArgs cmd) {
         Player player = cmd.getPlayer();
 
-        player.teleport(playerLocation.get(player));
-        player.sendMessage(CC.translate("&aSending you back to your previous death location."));
+        if (playerLocation.containsKey(player.getUniqueId())) {
+            player.teleport(playerLocation.get(player.getUniqueId()));
+            player.sendMessage(CC.translate("&aSending you back to your previous death location."));
+        } else {
+            player.sendMessage(CC.translate("&cYou have already used the /back command."));
+        }
+
+        playerLocation.remove(player.getUniqueId());
     }
 }

src/main/java/club/frozed/lunarutils/player/PlayerListener.java

@@ -26,11 +26,6 @@ public class PlayerListener implements Listener {
 
     private final LunarClientAPI lunarClientAPI = LunarClientAPI.getInstance();
 
-    /**
-     * On player join.
-     *
-     * @param event the event
-     */
     @EventHandler
     public void onPlayerJoin(PlayerJoinEvent event) {
         Player player = event.getPlayer();
@@ -69,8 +64,14 @@ public void onPlayerJoin(PlayerJoinEvent event) {
     public void onPlayerDeath(PlayerDeathEvent event) {
         Player player = Bukkit.getPlayer(event.getEntity().getUniqueId());
         if (event.getEntity() == player) {
-            BackCommand.playerLocation.put(player, player.getLocation());
+            BackCommand.playerLocation.put(player.getUniqueId(), player.getLocation());
         }
-        player.sendMessage(CC.translate("&cYou died, your last death location has been saved! &7&oUse /back to go back to it."));
+
+        player.sendMessage(CC.CHAT_BAR);
+        player.sendMessage(CC.translate("&4&lTe moriste pete XdxdxDXDXdXDxDXd."));
+        player.sendMessage(CC.translate(" "));
+        player.sendMessage(CC.translate("&cYou can only use the &o/back &ccommand &lONCE."));
+        player.sendMessage(CC.translate("&cThis will teleport you back to your death location."));
+        player.sendMessage(CC.CHAT_BAR);
     }
 }