Version 1.20.I am creating a plugin and getting a PlaceholderAPI error in Minecraft. The console gives me this error:

[18:02:29] [Server thread/ERROR]: Error occurred while enabling WarpManager v1.0 (Is it up to date?)
java.lang.NullPointerException: Cannot invoke "me.clip.placeholderapi.PlaceholderAPIPlugin.getLocalExpansionManager()" because the return value of "me.clip.placeholderapi.expansion.PlaceholderExpansion.getPlaceholderAPI()" is null

d!
I tried searching on the internet but without results. The error tells me that I haven’t registered PlaceholderAPI, but I have.
Here is my WarpManager class:

    @Override
    public void onEnable() {
        instance = this;
        if (!setupEconomy()) {
            getLogger().info("Vault non trovato o non caricato correttamente.");
            getServer().getPluginManager().disablePlugin(this);
            return;
        }
        saveDefaultConfig();
        setupDatabase();

        if (Bukkit.getPluginManager().isPluginEnabled("PlaceholderAPI")) {
            placeholderExpansion = new WarpPlaceholderExpansion(this);
            placeholderExpansion.register();

            getLogger().info("PlaceholderAPI trovato e l'espansione è stata registrata.");
        } else {
            getLogger().warning("PlaceholderAPI non è disponibile. L'espansione non sarà registrata.");
        }

       
        getCommand("warps").setExecutor(new WarpsCommand(placeholderExpansion));
        
    }

   

    
}

And here is my WarpPlaceholderExpansion class:

public class WarpPlaceholderExpansion extends PlaceholderExpansion {

    private final WarpManager plugin;
    private String warpName;
    private String warpState;
    private String warpOwner;
    private String warpPrice;

    public WarpPlaceholderExpansion(WarpManager plugin) {
        this.plugin = plugin;
    }

  

    @Override
    public String getIdentifier() {
        return "warp";
    }

    @Override
    public String getAuthor() {
        return plugin.getDescription().getAuthors().toString();
    }

    @Override
    public String getVersion() {
        return plugin.getDescription().getVersion();
    }

    public void setWarpData(String name, String state, String owner, String price) {
        this.warpName = name;
        this.warpState = state;
        this.warpOwner = owner;
        this.warpPrice = price;
    }

    @Override
    public String onPlaceholderRequest(Player player, String identifier) {
        if (warpName == null || warpState == null || warpOwner == null || warpPrice == null) {
            return "";
        }

        switch (identifier) {
            case "name":
                return warpName;
            case "state":
                return warpState;
            case "owner":
                return warpOwner;
            case "price":
                return warpPrice;
            default:
                return null;
        }
    }
}

The error tells me that I haven’t registered PlaceholderAPI, but I have.

I tried searching on the internet but without results.