Error cannot be an iterator block

So I ran into this error in my update function and I have no idea what it means, or what happened. It seemed to happen when I added my pause to my if statement. Here's the error...

error CS1624: The body of redical.Update()' cannot be an iterator block because void' is not an iterator interface type

Here's my code

     void Update () {
         RaycastHit hit;
         float distance;
         float waitTime;
 
         waitTime = 3.0f;
 
         if (Physics.Raycast (new Ray (CameraFacing.transform.position, CameraFacing.transform.rotation * Vector3.forward), out hit)) {
             distance = hit.distance;
             if(hit.collider.gameObject.tag == "found"){ 
                 yield return new WaitForSeconds (waitTime);
                 if(hit.collider.gameObject.tag == "found"){
                     foundObject = hit.collider.gameObject; 
                     Destroy(foundObject);
                     //x++;
                     //print(x);
                 }
             } 
         } else {
             distance = CameraFacing.farClipPlane * 0.95f;
         }
         transform.position = CameraFacing.transform.position + CameraFacing.transform.rotation * Vector3.forward * distance;
         transform.LookAt (CameraFacing.transform.position);
         transform.Rotate (0.0f, 180.0f, 0.0f); 
     }
 }