Variable from other script causes NullReferenceException

Unity Engine
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1

I really can’t understand why i cant connect variable from other script with UI text. Console on load says me error

NullReferenceException: Object reference not set to an instance of an object
UISHIT.Update () (at Assets/SCRIPTS/UISHIT.cs:22)

My code in UI script:

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using TMPro;
using UnityEngine.Playables;
using System.Runtime.InteropServices.WindowsRuntime;

public class UISHIT : MonoBehaviour
{
    //stamina text
    public TextMeshProUGUI input;
    //trying to get access to variable in other script
    public readonly SC_FPSController Stamina;


    void Awake()
    {
    //trying to get access to variable in other script again
        GetComponent<SC_FPSController>();
    }
    void Update()
    {
        input.SetText(Stamina.ToString());
    }
    

}

Variable in other script

public static float Stamina = 100.0f;