I have a problem with Unity

This is the script that has a compiling error "MinMaxSliderDrawer"




using UnityEngine;
using UnityEditor;

[CustomPropertyDrawer (typeof (MinMaxSliderAttribute))]
class MinMaxSliderDrawer : PropertyDrawer {

public override void OnGUI (Rect position, SerializedProperty property, GUIContent label) {

if (property.propertyType == SerializedPropertyType.Vector2)
{
Vector2 range = property.vector2Value;
float min = range.x;
float max = range.y;
MinMaxSliderAttribute attr = attribute as MinMaxSliderAttribute;

EditorGUI.BeginChangeCheck ();
EditorGUILayout.BeginHorizontal();
EditorGUI.MinMaxSlider (label, new Rect(position.x,position.y,position.width - 106,position.height), ref min, ref max, attr.min, attr.max);
if (EditorGUI.EndChangeCheck ())
{
range.x = min;
range.y = max;
property.vector2Value = range;
}
EditorGUI.TextField(new Rect(position.x + position.width-50,position.y,50,position.height),range.y.ToString("0.00"));
EditorGUI.TextField(new Rect(position.x + position.width-102,position.y,50,position.height),range.x.ToString("0.00"));
EditorGUILayout.EndHorizontal();

} else {
EditorGUI.LabelField (position, label, "Use only with Vector2");
}
}