KeyNotFoundException in animator

Hello everyone.

I am trying to animate a sprite while it moves towards the player in Unity 2017.1.1f1.. After editting the sprites, creating the animations and coding I tested the game and it worked perfectly. However, after making a few changes that I had to undo because they weren't working as I wanted them to, I tested again and noticed that the horizontal walking animation wasn't working anymore. When I opened the animator tab there was this message on the console tab:

KeyNotFoundException:The given key was not present in the dictionary. UnityEngine.GUIUtility:ProcessEvent(Int32, IntPtr)

Here's a screenshot:

And here's the code, in case it's a programming issue:

 using System.Collections;
 using System.Collections.Generic;
 using UnityEngine;
 
 public class EnemyControls : MonoBehaviour {
 
     public Transform target;
     Animator anim;
 
     int direction, state;
     float speed, timer;
 
     void Move()
     {
         //horizontal movement: move left
         if (transform.position.x - target.position.x > 0.3f) {
             direction = 1;
             state = 1;
             anim.SetInteger ("direction", direction);
             anim.SetInteger ("state", state);
             transform.Translate (-transform.right * speed * Time.deltaTime);
         } 
 
         //horizontal movement: move right
         else if (transform.position.x - target.position.x < -0.3f) {
             direction = 3;
             state = 1;
             anim.SetInteger ("direction", direction);
             anim.SetInteger ("state", state);
             transform.Translate (transform.right * speed * Time.deltaTime);
         } 
 
         //horizontal movement: stop
         else {
             state = 0;
             anim.SetInteger ("state", state);
         }
 
         //vertical movement: move down
         if (transform.position.y - target.position.y > 0.3f) {
             direction = 0;
             state = 1;
             anim.SetInteger ("direction", direction);
             anim.SetInteger ("state", state);
             transform.Translate (-transform.up * speed * Time.deltaTime);
         } 
 
         //vertical movement: move up
         else if (transform.position.y - target.position.y < -0.3f) {
             direction = 2;
             state = 1;
             anim.SetInteger ("direction", direction);
             anim.SetInteger ("state", state);
             transform.Translate (transform.up * speed * Time.deltaTime);
         } 
 
         //vertical movement: stop
         else {
             state = 0;
             anim.SetInteger ("state", state);
         }
     }
 
     // Use this for initialization
     void Start () 
     {
         anim = GetComponent<Animator> ();
         target = GameObject.FindWithTag ("Player").transform;
         speed = 1.0f;
         state = 0;
     }
     
     // Update is called once per frame
     void Update () 
     {
         Move ();
     }
 }
 

I appreciate any help you can provide.