am getting this error in my script - `EnemyAI.CheckGround(UnityEngine.Vector3)': not all code paths return a value

here is my script the error is on line 78 Vector3 CheckGround (Vector3 pos) { I have tried several ways to correct this but still coming up with the same issue - how do I go about writing this code so I can fix this error or what do I need to change in the script so this can work properly - I tried using a debugger but of course it wouldn't tell me a solution on how to fix the issue. - if anyone can help me I would appreciate it

thanks in advance

public class EnemyAI : MonoBehaviour {

 public float gravity;
 public Vector2 velocity;
 public bool isWalkingLeft = true;

 LayerMask floorMask;

 private bool grounded = false;

 private enum EnemyState {

     walking,
     falling,
     dead
 }

 private EnemyState state = EnemyState.falling;

 // Use this for initialization
 void Start () {

     enabled = false;

     fall ();
 
 }
 
 // Update is called once per frame
 void Update () {

     UpdatedEnemyPosition ();
 
 }

 void UpdatedEnemyPosition () {

     if (state != EnemyState.dead) {

         Vector3 pos = transform.localPosition;
         Vector3 scale = transform.localScale;

         if (state == EnemyState.falling) {

             pos.y += velocity.y * Time.deltaTime;

             velocity.y -= gravity * Time.deltaTime;
         }

         if (state == EnemyState.walking) {

             if (isWalkingLeft) {

                 pos.x -= velocity.x * Time.deltaTime;

                 scale.x = -1;

             } else {

                 pos.x += velocity.x * Time.deltaTime;
                 
                 scale.x = 1;

             }
         }

         if (velocity.y <= 0)
             pos = CheckGround (pos);

         transform.localPosition = pos;
         transform.localScale = scale;
     }
 }

  Vector3 CheckGround (Vector3 pos) {

     Vector2 originLeft = new Vector2 (pos.x - 0.5f + 0.2f, pos.y - .05f);
     Vector2 originMiddle = new Vector2 (pos.x, pos.y - .5f);
     Vector2 originRight = new Vector2 (pos.x + 0.5f + 0.2f, pos.y - .05f);

     RaycastHit2D groundLeft = Physics2D.Raycast (originLeft, Vector2.down, velocity.y * Time.deltaTime, floorMask);
     RaycastHit2D groundMiddle = Physics2D.Raycast (originMiddle, Vector2.down, velocity.y * Time.deltaTime, floorMask);
     RaycastHit2D groundRight = Physics2D.Raycast (originRight, Vector2.down, velocity.y * Time.deltaTime, floorMask);

     if (groundLeft.collider != null || groundMiddle.collider != null || groundRight.collider != null) { 

         RaycastHit2D hitRay = groundLeft;
         
         if (groundLeft) {
             hitRay = groundLeft;
         } else if (groundMiddle) {
             hitRay = groundMiddle;
         } else if (groundRight) {
             hitRay = groundRight;

         }

         pos.y = hitRay.collider.bounds.center.y + hitRay.collider.bounds.size.y / 2 + .5f;

         grounded = true;
         
         velocity.y = 0;

         state = EnemyState.walking;

     } else {
         
         if (state != EnemyState.falling) {
             
             fall ();
         }
     }
 }


     void OnBecameVisible () {

     enabled = true;
 }

 void fall () {

     velocity.y = 0;

     state = EnemyState.falling;

     grounded = false;
 }

}