I need help with my abnormal plugin type error

Hi so I'm coding a plugin where a random potion effect is given and the code is this:

Code:

package me.goldk.max;


import org.bukkit.entity.Player;
import org.bukkit.event.EventHandler;
import org.bukkit.event.player.PlayerJoinEvent;
import org.bukkit.potion.PotionEffect;
import org.bukkit.potion.PotionEffectType;
import java.util.Random;
import org.bukkit.plugin.java.JavaPlugin;
import org.bukkit.event.Listener;



public class Main extends JavaPlugin implements Listener {
   
public Main (Main plugin) {                       
}


    @EventHandler
public void onPlayerJoin(PlayerJoinEvent event) {
        Player player =  (Player) event.getPlayer();
        Random rand = new Random();
          int chance = 1;
          if (chance == 0)
          {
        player.addPotionEffect(new PotionEffect(PotionEffectType.INVISIBILITY, 60, 1));

          }
          else if (chance == 1)
          {
              player.addPotionEffect(new PotionEffect(PotionEffectType.SPEED, 60, 1)); 
          }
          return;
}
}

but when I put the jar file into my spigot server pro server I got an error that says this:

Code:

Could not load 'plugins/max.jar' in folder 'plugins'

org.bukkit.plugin.InvalidPluginException: Abnormal plugin type

at org.bukkit.plugin.java.PluginClassLoader.<init>(PluginClassLoader.java:80) ~[spigot-1.16.2.jar:git-Spigot-b5a13e6-0491200]

at org.bukkit.plugin.java.JavaPluginLoader.loadPlugin(JavaPluginLoader.java:135) ~[spigot-1.16.2.jar:git-Spigot-b5a13e6-0491200]

at org.bukkit.plugin.SimplePluginManager.loadPlugin(SimplePluginManager.java:394) ~[spigot-1.16.2.jar:git-Spigot-b5a13e6-0491200]

at org.bukkit.plugin.SimplePluginManager.loadPlugins(SimplePluginManager.java:301) ~[spigot-1.16.2.jar:git-Spigot-b5a13e6-0491200]

at org.bukkit.craftbukkit.v1_16_R2.CraftServer.loadPlugins(CraftServer.java:381) ~[spigot-1.16.2.jar:git-Spigot-b5a13e6-0491200]

at net.minecraft.server.v1_16_R2.DedicatedServer.init(DedicatedServer.java:186) ~[spigot-1.16.2.jar:git-Spigot-b5a13e6-0491200]

at net.minecraft.server.v1_16_R2.MinecraftServer.w(MinecraftServer.java:808) ~[spigot-1.16.2.jar:git-Spigot-b5a13e6-0491200]

at net.minecraft.server.v1_16_R2.MinecraftServer.lambda$0(MinecraftServer.java:164) ~[spigot-1.16.2.jar:git-Spigot-b5a13e6-0491200]

at java.lang.Thread.run(Thread.java:748) [?:1.8.0_212]

Caused by: java.lang.InstantiationException: me.goldk.max.Main

at java.lang.Class.newInstance(Class.java:427) ~[?:1.8.0_212]

at org.bukkit.plugin.java.PluginClassLoader.<init>(PluginClassLoader.java:76) ~[spigot-1.16.2.jar:git-Spigot-b5a13e6-0491200]

... 8 more

Caused by: java.lang.NoSuchMethodException: me.goldk.max.Main.<init>()

at java.lang.Class.getConstructor0(Class.java:3082) ~[?:1.8.0_212]

at java.lang.Class.newInstance(Class.java:412) ~[?:1.8.0_212]

at org.bukkit.plugin.java.PluginClassLoader.<init>(PluginClassLoader.java:76) ~[spigot-1.16.2.jar:git-Spigot-b5a13e6-0491200]

... 8 more

does anyone know how to help? if you can that would be greatly appriciated

 

@timtower I am really dumb and I'm sorry for bothering you but what is the constructor

 

Your (only) constructor requires an instance of itself, which is interesting lol.

But a constructor is unnecessary here so do as tim said.