Character suddenly stops at certain point when following AI (Img)

// Make sure there is always a character controller @script RequireComponent (CharacterController)

//function Awake() { // target = transform; //}

function Start () { if (!this.enabled) return;

 // Auto setup player as target through tags
 if (target == null && GameObject.FindWithTag("Player"))
     target = GameObject.FindWithTag("Player").transform;

 Patrol();

}

function Patrol () { if (!this.enabled) return;

 var curWayPoint = AutoWayPoint.FindClosest(transform.position);
 while (true) {
     var waypointPosition = curWayPoint.transform.position;
     // Are we close to a waypoint? -> pick the next one!
     if (Vector3.Distance(waypointPosition, transform.position) < pickNextWaypointDistance)
         curWayPoint = PickNextWaypoint (curWayPoint);

     // Attack the player and wait until
     // - player is killed
     // - player is out of sight     
     if (CanSeeTarget ())
         yield StartCoroutine("AttackPlayer");

     // Move towards our target
     MoveTowards(waypointPosition);

     yield;
 }

}

function CanSeeTarget () : boolean { if (!this.enabled) return;

 if (Vector3.Distance(transform.position, target.position) > attackRange)
     return false;

 var hit : RaycastHit;
 if (Physics.Linecast (transform.position, target.position, hit))
     return hit.transform == target;

 return false;

}

function Shoot () { if (!this.enabled) return;

 // Start shoot animation
 animation.CrossFade("shoot", 0.3);

 // Wait until half the animation has played
 yield WaitForSeconds(delayShootTime);

 // Fire gun
 BroadcastMessage("Fire");

 // Wait for the rest of the animation to finish
 yield WaitForSeconds(animation["shoot"].length - delayShootTime);

}

function AttackPlayer () { if (!this.enabled) return;

 var lastVisiblePlayerPosition = target.position;
 while (true) {
     if (CanSeeTarget ()) {
         // Target is dead - stop hunting
         if (target == null)
             return;

         // Target is too far away - give up 
         var distance = Vector3.Distance(transform.position, target.position);
         if (distance > shootRange * 3)
             return;

         lastVisiblePlayerPosition = target.position;
         if (distance > dontComeCloserRange)
             MoveTowards (lastVisiblePlayerPosition);
         else
             RotateTowards(lastVisiblePlayerPosition);

         var forward = transform.TransformDirection(Vector3.forward);
         var targetDirection = lastVisiblePlayerPosition - transform.position;
         targetDirection.y = 0;

         var angle = Vector3.Angle(targetDirection, forward);

         // Start shooting if close and play is in sight
         if (distance < shootRange && angle < shootAngle)
             yield StartCoroutine("Shoot");
     } else {
         yield StartCoroutine("SearchPlayer", lastVisiblePlayerPosition);
         // Player not visible anymore - stop attacking
         if (!CanSeeTarget ())
             return;
     }

     yield;
 }

}

function SearchPlayer (position : Vector3) { if (!this.enabled) return;

 // Run towards the player but after 3 seconds timeout and go back to Patroling
 var timeout = 3.0;
 while (timeout > 0.0) {
     MoveTowards(position);

     // We found the player
     if (CanSeeTarget ())
         return;

     timeout -= Time.deltaTime;
     yield;
 }

}

function RotateTowards (position : Vector3) { if (!this.enabled) return;

 SendMessage("SetSpeed", 0.0);

 var direction = position - transform.position;
 direction.y = 0;
 if (direction.magnitude < 0.1)
     return;

 // Rotate towards the target
 transform.rotation = Quaternion.Slerp (transform.rotation, Quaternion.LookRotation(direction), rotationSpeed * Time.deltaTime);
 transform.eulerAngles = Vector3(0, transform.eulerAngles.y, 0);

}

function MoveTowards (position : Vector3) { if (!this.enabled) return;

 var direction = position - transform.position;
 direction.y = 0;
 if (direction.magnitude < 0.5) {
     SendMessage("SetSpeed", 0.0);
     return;
 }

 // Rotate towards the target
 transform.rotation = Quaternion.Slerp (transform.rotation, Quaternion.LookRotation(direction), rotationSpeed * Time.deltaTime);
 transform.eulerAngles = Vector3(0, transform.eulerAngles.y, 0);

 // Modify speed so we slow down when we are not facing the target
 var forward = transform.TransformDirection(Vector3.forward);
 var speedModifier = Vector3.Dot(forward, direction.normalized);
 speedModifier = Mathf.Clamp01(speedModifier);

 // Move the character
 direction = forward * speed * speedModifier;
 GetComponent (CharacterController).SimpleMove(direction);

 SendMessage("SetSpeed", speed * speedModifier, SendMessageOptions.DontRequireReceiver);

}

function PickNextWaypoint (currentWaypoint : AutoWayPoint) { if (!this.enabled) return;

 // We want to find the waypoint where the character has to turn the least

 // The direction in which we are walking
 var forward = transform.TransformDirection(Vector3.forward);

 // The closer two vectors, the larger the dot product will be.
 var best = currentWaypoint;
 var bestDot = -10.0;
 for (var cur : AutoWayPoint in currentWaypoint.connected) {
     var direction = Vector3.Normalize(cur.transform.position - transform.position);
     var dot = Vector3.Dot(direction, forward);
     if (dot > bestDot && cur != currentWaypoint) {
         bestDot = dot;
         best = cur;
     }
 }

 return best;