❔ UNITY Code only fully executes after running it another time

public void DestroyCities()
    {
        for (int i = 0; i < transform.childCount; i++) 
        {
            GameObject go = transform.GetChild(i).gameObject;
            StartCoroutine(DestroyFastly(go));
        }

        /*for (int i = 0; i < transform.childCount; i++) 
        {
            GameObject go = transform.GetChild(i).gameObject;
            StartCoroutine(DestroyFastly(go));
        }*/
    }

    private IEnumerator DestroyFastly(GameObject go)
    {
        yield return new WaitForSeconds(0);
        DestroyImmediate(go, false);
    }

public void DestroyCities()
    {
        for (int i = 0; i < transform.childCount; i++) 
        {
            GameObject go = transform.GetChild(i).gameObject;
            StartCoroutine(DestroyFastly(go));
        }

        /*for (int i = 0; i < transform.childCount; i++) 
        {
            GameObject go = transform.GetChild(i).gameObject;
            StartCoroutine(DestroyFastly(go));
        }*/
    }

    private IEnumerator DestroyFastly(GameObject go)
    {
        yield return new WaitForSeconds(0);
        DestroyImmediate(go, false);
    }

public static class CreateCountryColors
        {
            private static Color[] colors = {
                Color.blue,
                Color.cyan,
                Color.green,
                Color.magenta,
                Color.red,
                Color.yellow
            };

            private static int colorIndex = 0;

            public static void Create(string path)
            {
                Countries countries = new Countries();
                countries = countries.CreateJSON();

                foreach (feature countryData in countries.features)
                {
                    string code = countryData.properties.ISO_A2.ToUpper();

                    Material countryMaterial = new Material(Shader.Find("HDRP/Lit"));
                    countryMaterial.color = colors[colorIndex];
                    
                    if (colorIndex == colors.Length - 1)
                        colorIndex = 0;
                    else
                        colorIndex++;

                    do {
                        AssetDatabase.CreateAsset(countryMaterial, $"{path}/{code}.mat");
                    } while (AssetDatabase.LoadAssetAtPath<Material>($"{path}/{code}.mat") == null);
                }
            }
        }

public static class CreateCountryColors
        {
            private static Color[] colors = {
                Color.blue,
                Color.cyan,
                Color.green,
                Color.magenta,
                Color.red,
                Color.yellow
            };

            private static int colorIndex = 0;

            public static void Create(string path)
            {
                Countries countries = new Countries();
                countries = countries.CreateJSON();

                foreach (feature countryData in countries.features)
                {
                    string code = countryData.properties.ISO_A2.ToUpper();

                    Material countryMaterial = new Material(Shader.Find("HDRP/Lit"));
                    countryMaterial.color = colors[colorIndex];
                    
                    if (colorIndex == colors.Length - 1)
                        colorIndex = 0;
                    else
                        colorIndex++;

                    do {
                        AssetDatabase.CreateAsset(countryMaterial, $"{path}/{code}.mat");
                    } while (AssetDatabase.LoadAssetAtPath<Material>($"{path}/{code}.mat") == null);
                }
            }
        }