Look for MeshFilter in child objects ONLY

Scripting
1

I am trying to change the vertex color of an object placed using an instantiation, but I receive an error on the parent object as it has no MeshFilter component.

What I need to do is effect the child objects without checking the parent, to avoid this error.

The code for this is between lines 33 and 46.

using UnityEngine;
using UnityEngine.UI;
using System.Collections;

public class ObjectPlacement : MonoBehaviour {

    public Text currentPrefab;

    protected GameObject instantiated;

    Ray ray;
    float rayDist;
    Vector3 lookPosition;
    Plane world = new Plane(Vector3.up, Vector3.zero); //world plane to draw the grid on
    Camera cam;

    bool isPreview = false;
    bool isPlaced = false;

    void Start()
    {
        cam = GetComponent<Camera>();
    }

    void Update()
    {
        ray = cam.ScreenPointToRay(new Vector3(Screen.width / 2, Screen.height / 2, 0));
        world.Raycast(ray, out rayDist);
        lookPosition = ray.GetPoint(rayDist);

        if(isPreview)
        {
            Transform[] allChildren = GetComponentsInChildren<Transform>();
            foreach (Transform child in allChildren)
            {
                Debug.Log(allChildren);
                Mesh mesh = instantiated.GetComponent<MeshFilter>().mesh;
                Vector3[] vertices = mesh.vertices;
                Color[] colors = new Color[vertices.Length];
                int i = 0;
                while (i < vertices.Length)
                {
                    colors[i] = Color.Lerp(Color.green, Color.green, vertices[i].y);
                    i++;
                }
            }
        }
    }

    public void selectPrefab(GameObject prefab)
    {
        if(prefab != null)
        {
            Vector3 rounedPos = new Vector3(Round(lookPosition.x), 0, Round(lookPosition.z));
            Vector2 mouse = Input.mousePosition;
            Vector3 finalPosition = lookPosition;
            finalPosition.x = GetMultiple(lookPosition.x, 3);
            finalPosition.y = GetMultiple(lookPosition.y, 3);
            finalPosition.z = GetMultiple(lookPosition.z, 3);
            instantiated = Instantiate(prefab, finalPosition, Quaternion.identity) as GameObject;
            isPreview = true;
        }
    }

    float Round(float x)
    {
        return Mathf.Round(x / 3) * 3;
    }

    int GetMultiple(float x, int multipleOf)
    {
        return ((int)((x / multipleOf) + 0.5f)) * multipleOf;
    }
}
2

I have since tried changing the code between lines 33 and 46 to this:

GameObject[] allChildren = instantiated.GetComponentsInChildren<GameObject>();
            foreach (GameObject child in allChildren)
            {
                Debug.Log(allChildren);
                Mesh mesh = child.GetComponent<MeshFilter>().mesh;
                Vector3[] vertices = mesh.vertices;
                Color[] colors = new Color[vertices.Length];
                int i = 0;
                while (i < vertices.Length)
                {
                    colors[i] = Color.Lerp(Color.green, Color.green, vertices[i].y);
                    i++;
                }
            }

But I keep getting the following error on line 33.

ArgumentException: GetComponent requires that the requested component ‘GameObject’ derives from MonoBehaviour or Component or is an interface.
UnityEngine.GameObject.GetComponentsInChildren[GameObject] (Boolean includeInactive) (at C:/buildslave/unity/build/artifacts/generated/common/runtime/UnityEngineGameObjectBindings.gen.cs:165)
UnityEngine.GameObject.GetComponentsInChildren[GameObject] () (at C:/buildslave/unity/build/artifacts/generated/common/runtime/UnityEngineGameObjectBindings.gen.cs:182)
ObjectPlacement.Update () (at Assets/Scripts/Gameplay/DungeonQuest/MapEditor/ObjectPlacement.cs:33)

3 
MeshFilter[] meshFilters = instantiated.GetComponentsInChildren<MeshFilter>();
foreach(MeshFilter meshFilter in meshFilters) {
     if(meshFilter.gameObject == instantiated) {
            //if the currently iterated MF component is the root object's, continue since we want onyl those found on children
             continue;
     }
     //do whatever you want with the currently iterated child's MF component
}