rotate a 2D sprite towards mouse

I want to create a top-down 2D game and I have trouble with making the sprite rotate towards the mouse. When I boot up the game, the sprite sits there and does nothing. Here is my code

     using UnityEngine;
     using System.Collections;
 
     public class Aim : MonoBehaviour {
 
         private Vector3 mouse_pos;
         public Transform Player;
         private Vector3 object_pos;
         private float angle;
 
         void Update()
         {
             mouse_pos = Input.mousePosition;
             mouse_pos.z = -20;
             object_pos = Camera.main.WorldToScreenPoint(Player.position);
             mouse_pos.x = mouse_pos.x - object_pos.x;
             mouse_pos.y = mouse_pos.y - object_pos.y;
             angle = Mathf.Atan2(mouse_pos.y, mouse_pos.x) * Mathf.Rad2Deg;
             transform.rotation = Quaternion.Euler(0, 0, angle);
         }
     }