Why is Unity throwing error cs0411?

Question

C++ / C#

I'm learning Unity from Unity in Action. I am writing a code example from the book, but the engine swears at the error:
Assets\ReactiveTarget.cs(9,32): error CS0411: The type arguments for method 'Component.GetComponent()' cannot be inferred from the usage. Try specifying the type arguments explicitly.
As I understand it, the reason is that the example in the book is incorrect (since a similar error was previously, and was corrected by changing the syntax), but when changing the syntax from
WanderingAI behavior = GetComponent();
to

WanderingAI behavior = Component.GetComponent<WanderingAI>();

error cs0120 appears, since I refer to a non-static object, nothing is described in the book about this, attempts to make this object static throw even more errors, both codes are contained below
Wandering Ai

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

public class WanderingAI : MonoBehaviour
{
    public float speed = 3.0f;
    public float obstacleRange = 5.0f;

    private bool _alive;

    void Start()
    {
        _alive = true;
    }

    void Update()
    {
        if (_alive)
        { 
            transform.Translate(0, 0, speed * Time.deltaTime);

            Ray ray = new Ray(transform.position, transform.forward);
            RaycastHit hit;
            if (Physics.SphereCast(ray, 0.75f, out hit))
            {
                if (hit.distance < obstacleRange) 
                {
                    float angle = Random.Range(-100, 110);
                    transform.Rotate(0, angle, 0);
                }
            }
        }
    }

    public void SetAlive(bool alive)
    {
        _alive = alive;
    }
}

Reactive Target:

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

public class ReactiveTarget : MonoBehaviour
{
    public void ReactToHit()
    {
        WanderingAI behavior = GetComponent(); // Именно на эту строку ругается Unity(

        if (behavior != null)
        {
            behavior.SetAlive(false);
        }
        StartCoroutine(Die());
    }

    IEnumerator Die()
    {
        this.transform.Rotate(-75, 0, 0);

        yield return new WaitForSeconds(1.5f);

        Destroy(this.gameObject);
    }

    void Start()
    {
        
    }

    void Update()
    {
        
    }
}