Instantiating Enemy AI NavMesh Agent SetDestination Error

Short Version:

I'm getting this error: "SetDestination" can only be called on an active agent that has been placed on a NavMesh. EnemyAI:NewDestination(Vector3)(at../EnemyAI.cs:36)

• I do have a baked NavMesh

• The Method is working fine on the enemies that are FIRST instantiated by the spawner

• After the enemy dies and the Respawn method is invoked I SOMETIMES get this error

• Maybe about 10% of the time

• When this error pops up it spawns DOUBLE the number of enemies

• So I'll have 1, then 2, then 4, then 8, etc.

• It is only supposed to spawn 1 and then respawn it on death

Details:

I'm working on a respawning enemy and the way I went about it was to create a SpawnPoint prefab I can place into the world. It has a public gameObject variable called enemyType which I can assign any enemy prefab into.

EnemySpawn (Attached to the spawner gameobject):

 public class EnemySpawn : MonoBehaviour {
 
     public GameObject enemyType;
     
     void Start () {
         Spawn(0);
     }
     
     //Get ready to spawn the enemy
     public void Spawn(int respawnTime){
         Invoke("Respawn", respawnTime);
     }
 
     //Instantiate the enemy and set a reference to this spawnPoint's script
     public void Respawn(){
         GameObject go = Instantiate(enemyType, transform.position, transform.rotation) as GameObject;
         EnemyHealth eh = go.GetComponent ("EnemyHealth") as EnemyHealth;
         eh.spawnPoint = this;
     }
 }

The Enemy is spawned and it has two scripts: EnemyHealth and EnemyAI. EnemyHealth monitors it's health, unsurprisingly. :P When the health is at the appropriate level it's Die() method is called:

EnemyHealth: Attached to each enemy instance

 public class EnemyHealth : MonoBehaviour {
 
     public int targetsLeft = 0;
     public int cd_respawn = 0;
     //spawnPoint is set when instantiated by the spawner gameObject
     public EnemySpawn spawnPoint;
     
 
     void Die(){
         //As long as iti's respawnable and has a respawn point, respawn the enemy
         if(cd_respawn > 0 && spawnPoint != null){
             spawnPoint.Spawn (cd_respawn);
         }
         //Turn off the enemyAI so it stops the InvokeRepeating wandering stuff
         EnemyAI ai = this.GetComponent("EnemyAI") as EnemyAI;
         ai.Death ();
         
         //Destroy the current enemy
         Destroy(gameObject);
     }
 }

The Enemy AI by default goes into Wandering state where it picks random locations using an InvokeRepeating method "Wander". Wander does some random math then calls NewDestination which uses agent.SetDestination with that randomized number. I Split these into two methods so I could manually use NewDestination if I wanted to.

Enemy AI: Attached to each instance of the enemy

 public class EnemyAI : MonoBehaviour {
 
     public NavMeshAgent agent;
     private Vector3 startPosition;  
     //Variables ...
     //...
 
     void Awake(){
         //Get the NavMeshAgent so we can send it directions and set start position to the initial location
         agent = GetComponent("NavMeshAgent") as NavMeshAgent;
         agent.speed = wanderSpeed;
         startPosition = this.transform.position;
         InvokeRepeating("Wander", 1f, 5f);
     }
 
     void Wander(){
         //Pick a random location within wander-range of the start position and send the agent there
         Vector3 destination = startPosition + new Vector3(Random.Range (-wanderRange, wanderRange), 
                                                           0, 
                                                           Random.Range (-wanderRange, wanderRange));
         NewDestination(destination);
 
     }
 
     public void NewDestination(Vector3 targetPoint){
         //ERROR LOCATION ******* ERROR LOCATION ******* ERROR LOCATION ******** ERROR LOCATION
         //Sets the agents new target destination to targetPoint parameter
         agent.SetDestination (targetPoint);
     }
 
     //Other Enemy AI functions not related to setDestination here
     //...
     //...
 
     void StopChasing(){
         chasing = false;
         //Return Home then start wandering
         agent.speed = wanderSpeed;
         agent.SetDestination (startPosition);
         InvokeRepeating("Wander", 0.5f, 5f);
     }
     
     //I added this method thinking the issue was that Wander might still be invoking
     //It's called from EnemyHealth (Die) to make sure this AI stops before being deleted
     //To be sure that wasn't throwing the error.
     public void Death(){
         CancelInvoke();
     }
 
 } //Class End