Use of unassigned variable? Script from script reference

Hi, I’ve recently decided to start coding in c#, so today I was going to do some AI, but I started having this error: Assets/Scripts/EnemyScript.cs(23,16): error CS0165: Use of unassigned local variable `closestPlayer’ it’s weird because the script is almost the same from the script reference page, this is how my script is at the moment:

using UnityEngine;
using System.Collections;

public class EnemyScript : MonoBehaviour {

	public float health = 100;
	public float speed = 100;	
	GameObject FindClosestEnemy() {
        GameObject[] gos;
        gos = GameObject.FindGameObjectsWithTag("Player");
        GameObject closestPlayer;
        float distance = Mathf.Infinity;
        Vector3 position = transform.position;
        foreach (GameObject go in gos) {
            Vector3 diff = go.transform.position - position;
            float curDistance = diff.sqrMagnitude;
            if (curDistance < distance) {
                closestPlayer = go;
                distance = curDistance;
        return closestPlayer;

I can’t find any mistake in my script so I don’t understand what is wrong, by the way I also tried to call FindClosestEnemy() in the FixedUpdate void, the error was the same. Any help would be appreciated, thanks in advance.

Here is your problem:

GameObject closestPlayer;

To fix change to this:

GameObject closestPlayer = null;

That way if it fails to find an enemy it can return null and not throw an exception.