Struggeling with inverselerp and gradients and adding collider to code generated mesh.

Hi, I am currently following a Brackeys tutorial on procedural terrain generation colors. I got to a point where it gives me this error.

IndexOutOfRangeException: Index was outside the bounds of the array. mapgeneration.CreateShape () (at Assets/mapgeneration.cs:108)

mapgeneration.Update () (at Assets/mapgeneration.cs:131)

I am using gradiants to display color on my 108 is the line in create shape . This is the line

colors[iloopedforvertecy] = gradient.Evaluate(height);

In Advance, if someone helps me Greatly appreciated.

 using System.Collections;
 using System.Collections.Generic;
 using UnityEngine;
 
 
 [RequireComponent(typeof(MeshFilter))]
 public class mapgeneration : MonoBehaviour
 {
 
     Mesh mesh;
     Color[] colors;
     
     Vector3[] vertices;
     int[] triangles;
 
     public int xsize = 20;
     public int zsize = 20;
     [Range(1, 100)]
     public float smooth = 1.0f;
     public MeshCollider _mesh;
 
     public Transform water;
     public float scale;
     public float smoothfactor;
     
     public float xoffset = 0.0f;
     public float zoffset = 0.0f;
 
     public float minwaterheight;
     public float maxwaterheight;
 
     public float minterainheight;
     public float maxterainheight;
     public Gradient gradient;
 
     // Start is called before the first frame update
      void Start()
      {
         mesh = new Mesh();
         GetComponent<MeshFilter>().mesh = mesh;
 
         CreateShape();
         _mesh = GetComponent<MeshCollider>();
        
         water.transform.position = new Vector3(0, Random.Range(minwaterheight, maxwaterheight), 0);
        
      }
 
      void CreateShape()
      {
        vertices = new Vector3[(xsize + 1) * (zsize + 1)];
         water.transform.localScale = new Vector3(xsize,0,zsize);
        int iloopedforvertecy = 0;
 
       
 
         triangles = new int[xsize * zsize * 6];
        int vert = 0;
        int tris = 0;
 
        for(int z = 0; z < zsize; z++)
        {
             
        for(int x = 0; x < xsize; x++)
        {
        
        triangles[tris + 0] = vert + 0;
        triangles[tris + 1] = vert + xsize + 1;
        triangles[tris + 2] = vert + 1;
        triangles[tris + 3] = vert + 1;
        triangles[tris + 4] = vert + xsize + 1;
        triangles[tris + 5] = vert + xsize + 2;
 
        vert++;
        tris += 6;
        }  
        vert++;
        }
 
        colors = new Color[vertices.Length];
 
        for (int z = 0; z <= zsize; z++)
        {
              
               for(int x = 0; x <= xsize; x++)
               {
               float xCoord = (float)x / xsize * scale + xoffset;
               float zCoord = (float)z / zsize * scale + zoffset;
 
               
                  float y =  Mathf.PerlinNoise(xCoord * smooth, zCoord * smooth) * smoothfactor;
                 
                  vertices[iloopedforvertecy] = new Vector3(x, y, z);
                  iloopedforvertecy += 1;
 
                 
                if(y > maxterainheight){
                     maxterainheight = y;
                  }
 
                  if(y < minterainheight)
                  {
                       minterainheight = y;
                  }
 
                  float height = Mathf.InverseLerp(minterainheight, maxterainheight, 0.5f); //vertices[iloopedforvertecy].z
                  Debug.LogWarning(height);
                  colors[iloopedforvertecy] = gradient.Evaluate(height);
               }
        }
 
 
       
      }
 
     void UpdateMsh()
     {
         mesh.Clear();
 
         mesh.vertices = vertices;
         mesh.triangles = triangles;
 
         mesh.RecalculateNormals();
         
 
         mesh.colors = colors;
     }
 
     void Update()
     {
     CreateShape();
          UpdateMsh();
     }
 
 
   
  
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
 }
 

I know that my code is messy. Still new to coding and unity in general.

Oh PS. Can somebody please help me add a collider to code generated object as you can see in the code above? I have researched it and the use stuff I can not comprehend.