NullReferenceException: Object reference not set to an instance of an object Player.Start () (at Assets/Scripts/Player.cs:29)

So I cannot for the life of me figure out what I'm doing wrong here, I have looked everywhere and haven't found anything to help me.

Essentially I have two sliders, one for Health the other for Mana. no matter ho many different combinations I try I can't seem to be able to do anything with the sliders as I get the error above.

Here is my code.

 using System.Collections;
 using System.Collections.Generic;
 using UnityEngine;
 using UnityEngine.UI;
 
 public class Player : MonoBehaviour
 {
     public Slider HealthBar;
     public Slider ManaBar;
 
     private Slider Health;
     private Slider Mana;
 
     private float MaxHealth = 100;
     private float MaxMana = 40;
     private float CurrentHealth = 100;
     private float CurrentMana = 40;
     private float Level = 1;
     private float Armor = 5;
     private float MagRes = 0;
     private float Str = 10;
     private float Speed = 15;
 
     
 
     // Start is called before the first frame update
     void Start()
     {
         Health = HealthBar.GetComponent<Slider>();
         Mana = ManaBar.GetComponent<Slider>();
 
         CurrentHealth = MaxHealth;
         CurrentMana = MaxMana;
         Health.value = CurrentHealth;
         Mana.value = CurrentMana;
     }
 
     // Update is called once per frame
     void Update()
     {
         CurrentHealth -= Time.deltaTime;
         Health.value = CurrentHealth;
         CurrentMana -= Time.deltaTime;
         Mana.value = CurrentMana;
     }

and here is a screenshot of the Inspector as well.