Trying to get a 2d prefab without rigidbody to instantiate on button press, "the variable T_Bullet has not been assigned."

Full Code:

   using UnityEngine;
     using System.Collections;
     
 public class player_script : MonoBehaviour {
     public float speed = 8f;
     public float countdown = 3.0f;
     private bool m_Fired;
     public GameObject T_Bullet;
     // Use this for initialization
 
     void Start () {
     
     }
     
     // Update is called once per frame
     void Update () {
 
         if (Input.GetButton("Fire1"))
         { transform.Translate(Vector2.up * Time.deltaTime ); }
 
         if (Input.GetButton("Fire2"))
         { transform.Translate(Vector2.down * Time.deltaTime ); }
 
         if (Input.GetButton("Jump"))
         { Fire(); }
     }
 
     private void Fire()
     {
         Instantiate(T_Bullet,Vector2.right, Quaternion.identity);
 
     }
 }

Trying to get a bullet prefab to spawn when the spacebar is pressed, but the Console gives me that error message. Most of the other answers for this topic involve 2d Rigidbodies, which I have no reason to use for the sort of game I am making