How to fix jump error?

Question

Unity

Hello! I made controls for the character, everything works, but the jump is endless, and I don’t know what to do, although I seem to have set everything up correctly. Throws an error: "UnassignedReferenceException: The variable feetPos of HeroCntrl has not been assigned.
You probably need to assign the feetPos variable of the HeroCntrl script in the inspector." I put feetPos under the character, and highlight it in green, in the editor I put it under my feet, I select everything for all objects (Ground), but still there is such a problem. Please help me fix the error!

Here is the code:

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class HeroCntrl : MonoBehaviour
{
    public float speed = 10f;
    public float jumpForce;
    private float moveInput;

    Rigidbody2D rb;

    private bool FacingRight = false;

    private bool isGrounded;
    public Transform feetPos;
    public float checkRadius;
    public LayerMask WhatIsGround;

    private void Start()
    {
        rb = GetComponent<Rigidbody2D>();
    }

    private void Update()
    {
        isGrounded = Physics2D.OverlapCircle(feetPos.position, checkRadius, WhatIsGround);
        if (isGrounded = true && Input.GetKeyDown(KeyCode.Space))
        {
            rb.velocity = Vector2.up * jumpForce;

        }
    }
    private void FixedUpdate()
    {
        moveInput = Input.GetAxis("Horizontal");
        rb.velocity = new Vector2(moveInput * speed, rb.velocity.y);

        if (FacingRight = false && moveInput > 0)
        {
            Flip();
        }
        else if (FacingRight = true && moveInput < 0)
        {
            Flip();
        }
    }
    void Flip()
    {
        FacingRight = !FacingRight;
        Vector3 Scaler = transform.localScale;
        Scaler.x *= -1;
        transform.localScale = Scaler;
    }
}

Answer 1

In this course that you are doing, he says a hundred times why this can be.
In general, I advise you not to go through it, there are a lot of blunts)